List of abbreviations

G-I, G-II, G-III

Grubbs' catalysts 1st, 2nd or 3rd generation HG-I, HG-II Hoveyda-Grubbs '

GENERAL INTRODUCTION

Olefin metathesis (from the Greek word "μετάθεση", meaning change of position 1 ) is a reaction that entails the redistribution of substituents of alkenes by the scission and regeneration of new double bonds (Scheme 1).

Scheme 1. General scheme of olefin metathesis.

During the last decades, olefin metathesis has become one of the most powerful and attractive tools for the formation of carbon-carbon double bonds in synthesis of wide range of different molecules from simple alkenes 2 to complex biologically active compounds [3][4][5] and polymers 6 . The importance of the development of metathesis method in organic synthesis has been recognized by the award of the Nobel Prize in Chemistry for 2005 jointly to Yves Chauvin, Robert H. Grubbs, and Richard R. Schrock. The most efficient catalysts for the olefin metathesis reaction in homogeneous conditions have been developed with well-defined ruthenium 7 , molybdenum and tungsten 8 complexes featuring a reactive metal-carbene ligand. Among the variety of metathesis catalysts obtained up to now, ruthenium-based Grubbs-type catalysts (Figure 1) are very popular due to successful combination of remarkable air and moisture stability, relative tolerance to a wide range of functional groups (such as carboxylic acids, alcohols, ketones etc.) while maintaining good reactivity of ruthenium metal center to C=C double bond 9 . Since 1992, when the first well-defined ruthenium catalysts has been reported 10 , a large number of different modifications was performed [START_REF] Vougioukalakis | Ruthenium-Based Heterocyclic Carbene-Coordinated Olefin Metathesis Catalysts[END_REF] . Despite the great progress that has been made during recent decades, synthesis of novel, more efficient and selective metathesis catalysts is still of great interest.

The mechanism for metal-catalyzed olefin metathesis was suggested by Y. Chauvin and J.-L.

Hérisson [START_REF] Hérisson | Catalyse de Transformation Des Oléfines Par Les Complexes Du Tungstène. II. Télomérisation Des Oléfines Cycliques En Présence D'oléfines Acycliques[END_REF] . Accordingly (Scheme 2), the key steps of metathesis includes the [2+2]-cycloaddition of olefin to a carbene complex with formation of a metallacyclobutane intermediate followed by retro[2+2]cycloaddition. It is important to note that each step of the catalytic cycle is reversible.

Scheme 2. The general mechanism of olefin metathesis.

It entails that the result of metathesis in the most general case is an equilibrium mixture of all possible products. Thus, olefin metathesis as preparative method could be used only in the case of shifting equilibrium in one direction. This is illustrated by the formation of 5-or 6-membered unstrained (hetero)cycles or, the opposite, ring-strain release. Depending on olefin substrates, several common types of metathesis have been described (Scheme 3).

Scheme 3. Common types of olefin metathesis.

Scheme 3 (continuation).

Common types of olefin metathesis.

Among them, ring-closing metathesis (RCM) and ring-opening metathesis polymerization (ROMP) are the most widely used types of olefin metathesis in organic synthesis and polymer science, respectively. One the other hand, cross-metathesis (CM) is one of the most challenging types due to the absence of strong thermodynamic reasons for irreversibility of reaction and E/Zselectivity of products. While the problem of irreversibility could be solved by formation of volatile olefins as by-products (such as ethylene or propylene), mixture of E-and Z-olefins with thermodynamically favorable major E-product is hard to separate. On the other hand, many natural and biologically active compounds contain Z-alkene moieties. Therefore, synthesis of efficient catalysts that could provide formation of only E-or Z-olefins is one of the most topical tasks of metathesis catalysts modification. These aspects have recently found elegant solution by fine tuning of steric bulk of the ligands around the metal center [START_REF] Lam | Synthesis and Evaluation of Molybdenum and Tungsten Monoaryloxide Halide Alkylidene Complexes for Z-Selective Cross-Metathesis of Cyclooctene and Z-1,2-Dichloroethylene[END_REF][START_REF] Koh | Molybdenum Chloride Catalysts for Z-Selective Olefin Metathesis Reactions[END_REF][START_REF] Marx | Cyclometalated Ruthenium Alkylidene Complexes: A Powerful Family of Z-Selective Olefin Metathesis Catalysts BT -Ruthenium in Catalysis[END_REF] .

At the same time, the chemistry of fluorinated compounds is undergoing rapid growth.

Organofluorine compounds often show unusual properties and behavior in comparison with corresponding non-fluorinated parent compounds, due to unique properties of the fluorine atom, such as high electronegativity, small size and polarizability, ability to form H-bonding and coordinate to transition metals [START_REF] Plenio | The Coordination Chemistry of the CF Unit in Fluorocarbons[END_REF] , strength of the C-F bond, which is the strongest one in organic chemistry. Moreover, high abundance in Earth's crust and possibility of easy detection by 19 F NMR because of monoisotopicity and high sensitivity [START_REF] Fustero | Olefin Metathesis Reactions with Fluorinated Substrates, Catalysts, and Solvents[END_REF] are also attractive properties for chemists.

Due to this features organofluorine compounds have found a large variety of industrial applications in medicinal chemistry, crop, and material sciences. 5-Fluorouracil, Prozac, and Efavirenz are well-known examples of fluorine-containing drugs. Finally, perfluoroorganic derivatives can create a fluorous phase that is immiscible with most of organic solvents and can provide simple recovery of catalysts or reaction products 18 .

Up to date, only a few fluorine-containing ruthenium metathesis catalysts have been reported. In addition to the mentioned above fluorophilicity, which could be achieved due to perfluorosubstituents (i.e. "fluorous ponytails"), introduction of fluorine to the ligands of ruthenium metathesis catalysts might increase their electron withdrawing properties, steric bulk or create Ru-F interactions. These properties may significantly alter the catalyst activity and selectivity.

The main target of the present work is the development of efficient methods for the synthesis of series of new unsymmetrical imidazolinium salts, precursors of NHC-ligands that contain bulky hexafluoroisopropoxy group and the synthesis of corresponding Grubbs-and Hoveyda-type catalysts (Figure 2), as well as the investigation of their catalytic activity in model RCM and CM reactions. In chapter 1, the recent publications about fluoro-containing ruthenium metathesis catalysts, their synthesis and activity will be reviewed. In chapter 2 we will describe the results of our own investigations in this field. The experimental details and conclusions will be presented in chapter 3 and chapter 4, respectively.

CHAPTER I (Literature survey)

FLUORINE-CONTAINING RUTHENIUM CATALYSTS OF OLEFIN METATHESIS 1.1. Introduction

In the general case, Grubbs catalysts contain several different types of ligands (Figure 3). The first one is the reactive metal carbene ligand. In first-generation Grubbs catalyst (G-I) it is usually an arylidene (benzylidene) that directly participates in the [2+2] cycloaddition during metathesis. In the case of second-(G-II and HG-II) and third-generation (G-III) catalysts, a second type of carbene, a N-heterocyclic carbene is also present. Due to its electronic and steric properties, this ligand provides stability and efficiency to the catalyst. The third type is L-type ligands are phosphine (in G-I and G-II) or pyridine (in G-III). In the case of Hoveyda-type catalysts (HG-II) the L-type ligand is a part of the bidentate arylidene ligand and consists in a chelating alkoxy group. Finally, chlorides are the most common X-type ligands in Grubbs or Hoveyda-type catalysts. All these ligands can be modified in various ways depending on the particular task. During the last decades, a large number of Grubbs catalysts modifications have been described [START_REF] Vougioukalakis | Ruthenium-Based Heterocyclic Carbene-Coordinated Olefin Metathesis Catalysts[END_REF][START_REF] Fustero | Olefin Metathesis Reactions with Fluorinated Substrates, Catalysts, and Solvents[END_REF] and until now modifications for improvement of selectivity, stability, recyclability or simplification of products isolation have been an important driving task. Some of them could be solved due to modification by fluorine-containing groups. In this literature survey, we review all known fluorine-containing olefin metathesis ruthenium catalysts and the synthesis of the corresponding fluorinated ligands. This survey is divided into parts according to the type of fluorine-containing ligand. In each part, except 1.7, the chronological order has been chosen.

Fluorine in NHC-ligands

The first example of second-generation Grubbs-type catalyst with polyfluoroalkyl C6F13(CH2)2group on nitrogen of NHC-ligand was published by A. Fürstner and co-workers in 2001 19 . This modification was performed to increase the catalyst solubility in supercritical CO2. The fluorinated group was introduced by alkylation of readily available N-mesityl imidazole with C6F13(CH2)2I under refluxing in toluene for 4 days to afford the corresponding NHC precursor in good yield (Scheme 4) [START_REF] Gardiner | Dicationic Chelating N-Heterocyclic Carbene Complexes of Palladium: New Catalysts for the Copolymerisation of C2H4 and CO[END_REF] . The target catalyst 1 was obtained in moderate yield by conventional route included the phosphine ligand exchange reaction of commercially available Grubbs complex of firstgeneration with the NHC generated in situ from fluorinated imidazolium salt under the treatment of the latter with potassium tert-butylate (Scheme 4). The complex 1 has demonstrated an excellent solubility in supercritical carbon dioxide and good catalytic activity in RCM of N,Ndimetallyltosylamine.

Scheme 4. Synthesis of complex 1.

In 2002 A. Hoveyda et al. described the synthesis of the catalyst 2a (Figure 4) [START_REF] Gardiner | Dicationic Chelating N-Heterocyclic Carbene Complexes of Palladium: New Catalysts for the Copolymerisation of C2H4 and CO[END_REF] , containing bidentate chiral binaphthyl NHC-ligand. This catalyst was air-stable and active in series of asymmetric metathesis reactions (up to >98% ee). In 2003 synthesis and catalytic activity of fluorine-containing (2b and 2c, Figure 4) modifications of 2a were described [START_REF] Van Veldhuizen | Chiral Ru-Based Complexes for Asymmetric Olefin Metathesis: Enhancement of Catalyst Activity through Steric and Electronic Modifications[END_REF] . The corresponding binaphthyl ligand was synthesized by multistep method using transmetalation of silver complex for synthesis of target complex 2b (Scheme 5).

Scheme 5. Synthesis of complex 2b.

The introduction of CF3-groups allowed to significantly increase the activity of catalysts. For instance, in asymmetric ring-opening cross-metathesis (AROCM) of norbornenedicarboxylic anhydride and styrene the reaction rate increased in 3 times for catalyst 2b and in 160 times for 2c (Table 1). [START_REF] Ritter | Rate Acceleration in Olefin Metathesis through a Fluorine-Ruthenium Interaction[END_REF] . The catalyst 3a demonstrated much higher activity than parental G-II in RCM DEDAM, while 3b was less active then HG-II. Such difference was explained by possible Ru-F interaction, which stabilizes 14-e complex on the initiation step of catalyst 3a and hinders the access of olefin to ruthenium in catalyst 3b. Despite the relatively low activity of 3b, it showed good results in RCM to form tetrasubstituted olefins [START_REF] Berlin | Ruthenium-Catalyzed Ring-Closing Metathesis to Form Tetrasubstituted Olefins[END_REF] . The corresponding fluorinated precursor of NHC-ligand was synthesized from commercially available 2,6-difluoroaniline.

Scheme 6. Synthesis of complexes 3.

Another approach for synthesis of 3a using 1-bromo-2,6-difluorobenzene (Scheme 7) was proposed by C. Costabile et al. 24 . In that publication catalyst 3a was studied in the scope of RCM, ROMP and CM. Low stability of 3a under reaction conditions in dichloromethane was marked.

Scheme 7. Synthesis of complex 3a.

Unsymmetrical analogues of 3a and 3b (catalysts 4-7, Scheme 8) demonstrated similar tendencies in RCM, CM and ROMP [START_REF] Vougioukalakis | Ruthenium Olefin Metathesis Catalysts Bearing an N-Fluorophenyl-N-Mesityl-Substituted Unsymmetrical N-Heterocyclic Carbene[END_REF][START_REF] Vougioukalakis | Ruthenium-Based Olefin Metathesis Catalysts Coordinated with Unsymmetrical N-Heterocyclic Carbene Ligands: Synthesis, Structure, and Catalytic Activity[END_REF] : in all cases Grubbs-type catalysts were more active than Hoveydatype. Synthesis of NHC-ligand precursors for was done by the adapted method for unsymmetrical imidazolinium salts starting from corresponding fluoroanilines. In 2008 H. Plenio et al. described the synthesis of second-generation Grubbs-type catalysts bearing saturated and unsaturated NHC-ligands with fluorine in para-positions (8a and 8b, Scheme 9) [START_REF] Leuthäußer | π-Face Donor Properties of N-Heterocyclic Carbenes in Grubbs II Complexes[END_REF] .

Some electrochemical properties of these complexes were described without the catalytic activity.

Fluorine atom was introduced into aromatic substrate by Schiemann reaсtion. Synthesis of catalysts 9 and 10 (Scheme 10) bearing 1,2,4-triazol-5-ylidene ligands with pentafluorophenyl moiety and their test in asymmetrical metathesis reactions (ARCM and AROCM) were described by K. Grela et al. [START_REF] Gawin | Testing New Ruthenium Complexes Bearing Chiral 1,2,4-Triazol-5-ylidene-Ligands as Catalysts for Asymmetric Olefin Metathesis[END_REF] . The complexes demonstrated good enantioselectivity in AROCM of norbornenedicarboxylic anhydride with styrene, but demonstrated low conversions and stability compared to their non-fluorinated analogues. Also because of their low stability for all catalytic tests 9 and 10 have been prepared in situ.

Scheme 10. Synthesis of complexes 9 and 10.

The same group described indenylidene ruthenium catalyst bearing unsymmetrical NHC-ligand with pentafluorobenzyl group (complex 11, Scheme 11) [START_REF] Ablialimov | Structure, and Catalytic Activity of New Ruthenium(II) Indenylidene Complexes Bearing Unsymmetrical N-Heterocyclic Carbenes[END_REF] . In RCM DEDAM in air atmosphere [START_REF] Piola | Olefin Metathesis in Air[END_REF] catalyst 11 demonstrated higher activity and lower stability than commercially available catalyst M2. Synthesis of fluorine-containing ligand was started from pentafluorobenzaldehyde. For synthesis of complex 11 two approaches were used: 1) deprotonation of corresponding imidazolinium tetrafluoroborate; and 2) decomposition of pentafluorophenylic adduct. However, the latter proved to be less efficient.

Scheme 11. Synthesis of complex 11.

The modification of second-generation Hoveyda-Grubbs catalyst with perfluoroalkyl groups for increasing of their fluorophilicity was described by J. Kvíčala et al. [START_REF] Kvíčala | Experimental and Theoretical Study of Hoveyda-Grubbs Catalysts Modified by Perfluorohexyl Ponytail in the Alkoxybenzylidene Ligand[END_REF] . In this work, perfluoroalkyl substituents were introduced into both mesityl moieties of NHC-ligands and benzylidene ligands.

Synthesis of latter will be mentioned in the next part of this survey. For synthesis of fluorous NHCligands perfluoroalkyl groups were added by Heck cross-coupling of iodo-containing diamine with perfluorooctylethylene followed by ring-closing of imidazolium cycle and catalytic reduction of double bonds (Scheme 12). Scheme 12. Synthesis of complex 14.

Despite the presence of three fluorous ponytails in complex 14, its partition coefficient (Pi (FBS)

-the ratio of concentrations in each phase of Fluorous Biphasic System) between perfluoro(methylcyclohexane) (PFMC) and toluene is just Pi(FBS) = 0.16 that is too low for recovery of catalyst. The catalytic activity of complex 14 in RCM of DEDAM was moderate, not higher than HG-II. Earlier attempts to coordinate N,N'-dipolyfluoroalkyl-containing NHC-ligands without mesityl moieties to ruthenium (Scheme 13) were unsuccessful probably due to low stability of unhindered NHC complexes [START_REF] Skalický | Ag Complexes of NHC Ligands Bearing Polyfluoroalkyl And/or Polyfluoropolyalkoxy Ponytails. Why Are Polyethers More Fluorous Than Alkyls?[END_REF] .

Scheme 13. Attempt of synthesis of ruthenium fluorous complex.

Attempts for synthesis of fluorophilic metathesis catalyst were made by K. Grela et al. as well.

However, perfluoroalkyl-containing complexes 15a,b (Figure 5) also demonstrated low fluorophilicity: complex 15a was insoluble in PFMC, 15b in PFMC formed stable emulsion [START_REF] Szczepaniak | Towards "cleaner" olefin Metathesis: Tailoring the NHC Ligand of Second Generation Ruthenium Catalysts to Afford Auxiliary Traits[END_REF] . Due to these results 15a and 15b were not tested in metathesis. In 2016 R. Grubbs and coworkers described the synthesis of fluorine-containing derivatives of known Z-selective catalysts 22 [START_REF] Endo | Chelated Ruthenium Catalysts for Z-Selective Olefin Metathesis[END_REF] (Scheme 16) with chelating adamantyl-containing NHC-ligand and 24 [START_REF] Khan | Readily Accessible and Easily Modifiable Ru-Based Catalysts for Efficient and Z-Selective Ring-Opening Metathesis Polymerization and Ring-Opening/Cross-Metathesis[END_REF][START_REF] Koh | High-Value Alcohols and Higher-Oxidation-State Compounds by Catalytic Z-Selective Cross-Metathesis[END_REF] with dithiolate ligand (Scheme 17). All the catalysts were synthesized starting from commercially available fluorinated anilines. Adamantyl-containing complexes 23a-d showed good activity and Z-selectivity in series of cross-metathesis and homodimerization reactions, but they were not higher than for complex 22 [START_REF] Hartung | Selective Olefin Metathesis with Cyclometalated Ruthenium Complexes[END_REF] .

Fluorine in benzylidene ligands

The first Grubbs catalyst (33) for synthesis of library of small, medium and macrocyclic heterocyclic compounds using RCM followed by F-SPE [START_REF] Leach | A Fluorous-Tagged Linker from Which Small Molecules Are Released by Ring-Closing Metathesis[END_REF][START_REF] Morton | Synthesis of Natural-Product-Like Molecules with Over Eighty Distinct Scaffolds[END_REF] .

Scheme 24. Synthesis of complex 57.

Scheme 25. Ene-diene cross-metathesis.

W. Bannwarth and F. Michalek described the synthesis of another Hoveyda-type catalyst 44 containing perfluorooctyl group for non-covalent immobilization on fluorous silica gel (Scheme 26) [START_REF] Michalek | Application of a Grubbs-Hoveyda Metathesis Catalyst Noncovalently Immobilized by Fluorous-Fluorous Interactions[END_REF] . Catalytic activity of the resulting complex 44 was tested in several examples of RCM.

Immobilization of 44 on amphiphilic polymer conetwork (APCN) allowed to use it in RCM reactions in aqueous media [START_REF] Hensle | Ring-Closing Olefin Metathesis in the Aqueous Phase of Amphiphilic Conetworks Consisting of Fluorophilic and Hydrophilic Compartments[END_REF] . Synthesis of the corresponding perfluoroalkyl-containing styrene was performed using corresponding trialkylbromosilane [START_REF] Andrushko | perfluoroalkyl)silyl Entities as Unexpectedly Potent Tags for the Noncovalent Immobilization of Catalysts by Fluorous-Fluorous Interactions: Application to the Synthesis of Several Perfluoro-Tagged Ligands[END_REF] .

Scheme 26. Synthesis of complexes 44.

Covalent immobilization on the fluorous solid support through the benzylidene ligand of Hoveydatype catalyst was performed using siliceous mesocellular foam (MCF) (45e, Scheme 27) was described by J. Ying. A series of immobilized catalysts 45a-e were tested in RCM of diolefins [START_REF] Lim | Silica-Supported Catalysts for Ring-Closing Metathesis: Effects of Linker Group and Microenvironment on Recyclability[END_REF] .

Good results on recyclability were obtain. demonstrated good activities in scope of RCM, RCEYM and CM reactions, uncluding large scale [START_REF] Rix | Aminocarbonyl Group Containing Hoveyda-Grubbs-Type Complexes: Synthesis and Activity in Olefin Metathesis Transformations[END_REF][START_REF] Clavier | Towards Long-Living Metathesis Catalysts by Tuning the N-Heterocyclic Carbene (NHC) Ligand on Trifluoroacetamide-Activated Boomerang Ru Complexes[END_REF] . Pentafluoromethyl-containing complex 49a was found less active than 47a in RCM of DEAMM [START_REF] Mauduit | Complexes Catalytiques a Base de Ruthenium et Utilisation de Tels Complexes Pour La Metathese D'olefines[END_REF] . In all cases positive impact of NHCOCF3-groups on catalytic activity was shown.

DIPP-containing catalysts 48 were more efficient for unhindered substrates. Moreover, after silica gel chromatography the residual ruthenium contaminations in products of selected metathetic reactions were unusually low (less than 2.5 ppm). Such good purification was possible due to the formation of hydrogen bond between oxygen atom of trifluoroacetamide species and silica (see below Figure 7). Afterwards the activities of complexes 47a and 48a were investigated in RCM [START_REF] Mohapatra | Catalytic Activity Studies of Aminocarbonyl Group Containing Hoveyda-Grubbs-Type Complexes for the Syntheses of Herbarumin I and Stagonolide A[END_REF][START_REF] Borré | Terpenic Compounds as Renewable Sources of Raw Materials for Cross-Metathesis[END_REF] , CM [START_REF] Hemelaere | Ruthenium-Catalyzed One-Pot Synthesis of (E)-(2-Arylvinyl)boronates through an Isomerization/Cross-Metathesis Sequence from Allyl-Substituted Aromatics[END_REF][START_REF] Bonin | Cross-Metathesis of Fatty Acid Methyl Esters with Acrolein: An Entry to a Variety of Bifunctional Compounds[END_REF] and ethenolysis [START_REF] Bidange | Ruthenium Catalyzed Ethenolysis of Renewable Oleonitrile[END_REF] reactions of different substrates and were more active than the corresponding nonfluorinated catalysts. Thus, catalysts 47a and 48a showed satisfactory results in RCM for the formation of 16-membered bafilomycin macrolactone core on the model substrate (Table 2) 63 . Several attempts for synthesis of analogues of catalyst 47a for heterogeneous catalysis were described. For example, modification of 47a bearing an anthracenyl tag 53 (Scheme 31) was used for immobilization on TNF-grafted silica via the formation of charge-transfer complex, in which anthracene group is a donor and electron-deficient 2,4,7-trinitrofluoren-9-one (TNF) moiety is an acceptor [START_REF] Nasrallah | Immobilization of an Anthracene-Tagged Ruthenium Complex on a 2,4,7-Trinitrofluoren-9-one-Grafted Silica: Efficiency and Recyclability in Olefin Metathesis Reactions[END_REF] . The resulting immobilized catalyst 53@SiO2 kept high activity in RCM of DEDAM after four cycles and showed good yields and recyclization ability in another metathesis reaction such as RCM, RCEYM and CM.

Scheme 31. Synthesis of catalyst 53@SiO2.

The possibility of formation of strong hydrogen bond between trifluoroacetamide-containing complexes and silica was used for immobilization as well. Catalysts 47a and 48a (Figure 7) were immobilized on the silica without any surface treatment [START_REF] Solodenko | Silica Immobilized Hoveyda Type Pre-Catalysts: Convenient and Reusable Heterogeneous Catalysts for Batch and Flow Olefin Metathesis[END_REF][START_REF] Nasrallah | Direct Immobilization of Ru-Based Catalysts on Silica: Hydrogen Bonds as Non-Covalent Interactions for Recycling in Metathesis Reactions[END_REF] . The resulting catalytic systems demonstrated good activities in RCM, CM and RCEYM reactions in flow conditions. Significant decrease of catalytic activity of 47a@SiO2 and 48a@SiO2 was observed after fifth to seventh cycle. Immobilization of Hoveyda-type catalyst on reduced graphene oxide (rGO) was described last year (Scheme 32) [START_REF] Nasrallah | Non Covalent Immobilization of Pyrene-Tagged Ruthenium Complexes onto Graphene Surfaces for Recycling in Olefin Metathesis Reactions[END_REF] . The catalyst 54@rGO was tested in RCM of DEDAM, but its activity was significantly reduced after the second cycle. The catalyst 55 showed latent properties, like its non-fluorinated parent 56 [START_REF] Ben-Asuly | A Thermally Switchable Latent Ruthenium Olefin Metathesis Catalyst[END_REF] . For instance, in RCM of DEDAM at room temperature 55 was almost inactive, while at 80°C it was even more active than 56, however, in some cases polymerization and isomerization products were observed.

Moreover, complex 55 can be activated by UV irradiation in RCM of DEDAM and ROMP of COE. Latency of such sulfur-containing catalysts as 55 or 56 could be explained by preferred inactive in metathesis cis-form (Figure 8). Under UV irradiation or heating active trans-isomer is formed. The catalyst 57 with covalent chelating amide ligand (Scheme 34) was synthesized by K. Grela et al. using ligand exchange in presence of excess of pyridine [START_REF] Pietraszuk | Ruthenium-Amido Complexes: Synthesis, Structure, and Catalytic Activity in Olefin Metathesis[END_REF] . This catalyst was tested in RCM of DEDAM and DEAMM. In neutral medium activity of this catalyst was low, but in presence of HCl it was very active. Fluorine-containing catalyst 57 was more active, than its non-fluorinated analogue 58 only in RCM of DEDAM. Catalysts 62b [START_REF] Caijo | Screening of a Selection of Commercially Available Homogeneous Ru-Catalysts in Valuable Olefin Metathesis Transformations[END_REF] and 63b [START_REF] Borré | A Fast-Initiating Ionically Tagged Ruthenium Complex: A Robust Supported Pre-Catalyst for Batch-Process and Continuous-Flow Olefin Metathesis[END_REF] have demonstrated high activity and initiation rate in RCM of DEAMM.

It was found, that replacement of SIMes to SIPr for complexes 61c and 62c may significantly decrease initiation rate with increase of stability of catalyst in the same time [START_REF] Nelson | Synergic Effects Between N-Heterocyclic Carbene and Chelating Benzylidene-Ether Ligands Toward the Initiation Step of Hoveyda-Grubbs Type Ru Complexes[END_REF] . Anyway, high activity of catalyst 61c was due to the structure of benzylidene ligand.

In 2013 K. Grela et al. described synthesis and catalytic activity of series of Hoveyda-type catalysts with different electron-withdrawing groups [START_REF] Olszewski | A New Tool in the Toolbox: Electron-Withdrawing Group Activated Ruthenium Catalysts for Olefin Metathesis[END_REF] . For fine-tuning of catalysts perfluorosulfane (weak EWG, 64a) and perfluorosulfone (strong EWG, 64b) groups were used (Scheme 38).

Perfluoroalkyl group was introduces via nucleophilic substitution of perfluopropropyl iodide in presence of potassium carbonate. The initiation rate of catalyst 64b was very high, as it was expected, but this catalyst was found to be very unstable even in solid state in the freezer.

Scheme 38. Synthesis of complexes 64.

In the paper by J. Kvíčala et al. [START_REF] Kvíčala | Experimental and Theoretical Study of Hoveyda-Grubbs Catalysts Modified by Perfluorohexyl Ponytail in the Alkoxybenzylidene Ligand[END_REF] Bis-perfluoroalkyl-containing styrene 67 was almost inactive in the reaction with G-I, moreover, benzylidene ligand in the resulting complex 68 was not able at all for chelation (Scheme 40).

Inability for chelation of electronically pure benzylidene ligands in ruthenium complexes was for the first time described by K. Grela et al. [START_REF] Michrowska | Nitro-Substituted Hoveyda-Grubbs Ruthenium Carbenes: Enhancement of Catalyst Activity through Electronic Activation[END_REF] .

Scheme 40. Synthesis of styrene 67 and complex 68.

More recently, J. Kvíčala et al. synthesized complex 69 (Scheme 41) [START_REF] Hošek | Synthesis of Heavy Fluorous Ruthenium Metathesis Catalysts Using the Stereoselective Addition of Polyfluoroalkyllithium to Sterically Hindered Diimines[END_REF] . As in previous cases this complex has proved to be not a heavy fluorous one (its Pi(FBS) < 1). In RCM reactions catalyst 69 was slightly less active than HG-II. Scheme 41. Synthesis of complex 69.

Immobilization possibility of perfluoroalkyl-containing Hoveyda-type catalyst was described by M. Matsugi et al. [START_REF] Kobayashi | A Medium Fluorous Grubbs-Hoveyda 2nd Generation Catalyst for Phase Transfer Catalysis of Ring Closing Metathesis Reactions[END_REF] . They synthesized perfluorodecyl-containing catalyst 70 (Scheme 42) that was immobilized via hydrophobic interaction on Teflon. This catalytic system was the first example of Hoveyda-type complex that could transfer between solid and liquid phases in RCM conditions.

Such transfer was not possible of perfluorooctyl-containing complex 59a. Catalyst 70 demonstrated excellent results in RCM reactions and good ability for recyclization.

Scheme 42. Synthesis of complex 70.

In the recent research of M. Matsugi et al. eight new fluorous catalysts 71a-f and 72a,b (Figure 9)

and their catalytic activity in RCM have been described [START_REF] Kobayashi | Grubbs-Hoveyda Second-Generation Catalysts Activated by the Introduction of a Light Fluorous Tag onto the Bidentate Ligands[END_REF] . Introduction of fluorous tags was carried out using above mentioned methods (see Scheme 23). The highest activity was observed in case of 1-naphtyl-containing catalyst 71d.

Fluorine in indenylidene and allenylidene ligands

Along with the most common benzylidene ruthenium complexes, indenylidene ones are aslo efficient metathesis catalysts stable for harsh conditions. One the most important of their advantages is facile accessibility: indenylidene complex could be obtained by treatment of tris(triphenylphosphine)ruthenium(II) dichloride with 1-phenylpropargyl alcohol in acidic conditions. An intermediate allenylidene complex (73, Scheme 43) in most of cases could be isolated from the reaction mixture. Such method is general pathway for synthesis of not only ruthrenium indenylidene complexes, but other transition metals too [START_REF] Bruce | Transition Metal Complexes Containing Allenylidene, Cumulenylidene, and Related Ligands[END_REF] . Further transformations of complex 74 usually includes exchange of L-ligand from PPh3 to PCy3 using the excess of the latter. Due to this synthetically important bond between allenylindene and indenylindene complexes, fluorinated derivatives of both of them will be reviewed in the same part.

The first pentafluorophenyl-containing indenylidene catalyst 75 (Scheme 44) was described by M.

Holtcamp et al. [START_REF] Holtcamp | Metathesis Catalyst and Process for Use Thereof[END_REF] The catalyst 80 showed higher activity in RCM of N,N-diallyl tosylamide than its non-fluorinated analogue. However, it has proved to be less selective to give the RCM product along with a number of isomeric products depicted on Scheme 49.

Scheme 49. RCM of N,N-diallyltosylamide with the catalyst 80.

Fluorine in methylidene ligands

In 2001 R. Grubbs and co-workers obtained the first difluorocarbene ruthenium complex 81 during the investigation of challenging metathesis of 1,1-difluoroethylene using G-II (Scheme 50) [START_REF] Trnka | Olefin Metathesis with 1,1-Difluoroethylene[END_REF] . The resulting complex showed very low activity in ROMP of COD. Moreover, the products of a second turnover of metathesis of 1,1-difluoroethylene, namely ethylene and tetrafluoroethylene, were not observed in the product mixture, indicating that the reaction was not catalytic.

Scheme 50. Synthesis of complex 81.

Six years later M. Johnson et al. described synthesis of second and third-generation monofluoromethylidene complexes (82a and 82b, Scheme 51) [START_REF] Macnaughtan | Structure, and Olefin Metathesis Activity of Two Ruthenium Monofluoromethylidene Complexes[END_REF] . The method for synthesis of the ligand precursor β-fluorostyrene included the electrophilic fluorination of alkenyl trifluoroborate by Selectfluor in mild conditions [START_REF] Petasis | Facile Preparation of Fluorine-Containing Alkenes, Amides and Alcohols via the Electrophilic Fluorination of Alkenyl Boronic Acids and Trifluoroborates[END_REF] . The activity of catalysts 82a and 82b was not high, but it was higher than that of difluoromethylidene complex 81. Third generation catalyst 82b demonstrated higher initiation rate and lower stability in a solution than 82a.

Scheme 51. Synthesis of complexes 82.

Despite quite good stability of catalyst 82a in solid state, there was found a tendency to formation of carbide complex 83 in a solution in dichloromethane (Scheme 52).

Scheme 52. Formation of carbide complex 83.

The last known up to date monofluoromethylidene ruthenium complex 84 (Scheme 53) has been described in 2009 [START_REF] Macnaughtan | Cross-Metathesis of Vinyl Halides. Scope and Limitations of Ruthenium-Based Catalysts[END_REF]

Fluorine in L-type ligands

Ruthenium catalysts bearing fluorinated monodentate L-type ligands (phosphine and pyridine) will be reviewed in this section together with chelating ligands containing fluorine in L-coordinating moiety. Thus, the first ruthenium metathesis catalyst bearing chelating ligand with fluorinated Ltype moiety 85 has been described in 1998 by R. Grubbs et al. (Scheme 54) 97 . Catalyst 85 and series of its analogues with salicylaldimine ligands have found to be less active at room temperature with dramatically increase of reactivity at higher temperatures.

Scheme 54. Synthesis of complexes 85.

Non-chelating L-type ligands in Grubbs-type catalysts are normally labile, so change of L-type ligand to another one could be carried out quite fast. In 2001 R. Grubbs et al. described for the first time third-generation catalyst (G-III), that has been synthesized by treatment of G-II with an excess of pyridine (Scheme 55) [START_REF] Sanford | A Versatile Precursor for the Synthesis of New Ruthenium Olefin Metathesis Catalysts[END_REF] . In this part complex G-III will be considered as starting material for other ruthenium complexes, including modifications with phosphine ligands, for instance, commercially available electronically pure tris[p-(trifluoromethyl)phenyl]phosphine (complex 86). Notably, that less donating tris(perfluorophenyl)phosphine was inactive in the reaction with G-III. The resulting catalyst 86 showed higher activity than G-II in CM of acrylonitrile and allylbenzene and in ROMP of COD [START_REF] Love | A Practical and Highly Active Ruthenium-Based Catalyst That Effects the Cross Metathesis of Acrylonitrile[END_REF] .

Scheme 55. Synthesis of complex 86.

Another fluorinated phosphine complex has been described in 2003 100 . The catalyst 87 (Figure 10)

was synthesized in the same procedure as 86. However, 87 showed lower activity than 86 in ROMP of COD. Another approach for synthesis of ruthenium catalysts with fluorous L-type ligands was described in the recent publication of J. Gladysz et al. 106 Pyridine 91 was synthesized via Heck crosscoupling of 3,5-dibromopyridine and perfluorooctylethylene followed by hydrogenation (Scheme 58). Synthesis of third-generation complex 92 was carried out via alternation of ligand exchange of G-III with 2.1 equivalents of 91 at room temperature degassing at low temperature for complete removal of pyridine 107 .

Scheme 58. Synthesis of pyridine 91 and complex 92.

The catalyst 92 was tested in RCM reactions. Notable acceleration has been also observed using biphasic systems CH2Cl2/fluorous solvent like for phosphine-containing catalysts 89.

Fluorine in X-type ligands

The first ruthenium metathesis catalyst with fluorinated X-type ligand was described by R. Grubbs et al. in 1994 108 : The synthetic procedure included the exchange of chlorine in vinyliden complex 93 on trifluoroacetate group using the corresponding silver salt (Scheme 59).

Scheme 59. Synthesis of complexes 94.

The catalyst 94a was much more active in ROMP NBE than its non-fluorinated analogue with acetate as ligand 109,110 . Notably, that when methylene chloride was changed for hexane the reaction led to formation of binuclear complex 95 with two trifluoroacetate groups and one water molecule as bridging ligands. The similar products were obtained when G-I has been used as starting material (Scheme 60) 111,112 .

Scheme 60. Synthesis of complexes 95a-e.

Complex 95a demonstrated moderate activity in self-metathesis (SM) of internal olefins such as trans-4-decene and methyloleate. The performance of catalysts 95b and 95d was comparable with 95a. In contrast, pentfluorobenzoate-containing catalysts 95с and 95e were inactive in this reaction.

Later a series of four-coordinate complexes 97 containing bulky fluorinated Х-type ligands 113 was described by the same research group. Synthesis of catalysts 97a and 97b was performed by the treatment of 96 with excess of the corresponding CF3-containing alcohol (Scheme 61).

Scheme 61. Synthesis of complexes 97.

The complexes obtained (97a,b) have demonstrated moderate catalytic activity at 60°C and high activity at room temperature under acidic catalysis (in presence of HCl) in RCM of DEDAM.

This ligand exchange strategy was later utilized by M. Buchmeiser et al. in 2004Buchmeiser et al. in -2011 114-122 114-122 for the preparation of a number of second-generation Hoveyda-type and third-generation Grubbs-type catalysts bearing different fluoro-containing X-ligands (Figure 11). In all cases ligand exchange was performed by treatment with corresponding silver salts. In the big variety of metathetic reactions trifluoroacetate-containing complex 98b demonstrated higher activity than triflate-containing 98a 114 . Moreover, 98b, as its homologues 98c,d 117 , catalyzed cyclopolymerization of diethyldipropargylmalonate (DEDPM, Scheme 62), but not in living manner 115 .

Scheme 62. Cyclopolymerization of DEDPM.

The complexes 99a-c and 100a-c 115,116 were active in living polymerization of 1,6-heptadiines.

The elongation of perfluoroalkyl chain led to improving of polydispersity index of the resulting polyene 117 .

The catalyst 99a was also successfully tested in cyclopolymerization of hydroxyl-containing heptadiines that was impossible under molybdenum catalysis with Schroсk catalysts 118 . Moreover, catalysts 98b, 99а, 100а showed activity in cyclopolymerization of N,N-dipropargylamines 119 .

Complexes 98e and 101 were synthesized for evaluation of influence of bulky ligands on regioselectivity of cyclopolymerization of dipropargylic substrates 120 . Catalyst 102 have demonstrated high activity of cyclopolymerization of DEDPM, but was inactive in RCM of DEDMM 121 . Catalysts 103a-c and 98g demonstrated good activity in copolymerization of NBE with CPE 122 .

In addition, the usage of fluorinated X-type ligands as a linkage unit for immobilization of metathesis catalysts on fest phase or different polymeric supports was also investigated. Thus, J. The hexafluoroglutaric moiety has proved to be a useful linkage for heterogenic catalysis. Thus, M. Buchmeiser et al. 114,124,125 and D. Braddock et al. 126 successfully immobilized Grubbs catalysts on the polymer supports using this approach. For example, the catalysts 105a and 105b grafted on the amphiphilic oligomeric poly(2-oxazoline) (Figure 12) were able to polymerize of DEDPM in water media 115 . Moreover, the same hexafluoroglutaric linkage was utilized for grafting of Hoveyda-type catalysts on monolith polyetherketone column 124,125,127 and on silica gel [128][129][130] for flow reactors.

Furthermore, hexafluoroglutaric moiety was useful for synthesis of Ru-catalysts with amphiphilic (106) and ionic (107) ligands (Figure 13) 131,132 . The attempt to add aqueous hydrofluoric acid or its pyridine complex to 108 resulted in decomposition of the desired Ru-F complex 109d in several seconds (Scheme 65) 134 .

Scheme 65. Formation of unstable complex 109d.

The stable isopropyl-containing latent complexes 110-111 were described by K. Grela et al.

( In 2015 the same group described complex 121 (Figure 15) with very high fluorophilicity (Pi(FBS) = 27), however, its catalytic activity was not reported [START_REF] Hošek | Synthesis of Heavy Fluorous Ruthenium Metathesis Catalysts Using the Stereoselective Addition of Polyfluoroalkyllithium to Sterically Hindered Diimines[END_REF] . As result, frequently fluorine-containing X-type ligands in ruthenium metathesis catalysts are used both for activation of catalyst and for immobilization of catalysts on the solid or polymeric support.

Immobilized catalysts that were presented in this part were mentioned in several earlier reviews 141- 144 .

Conclusions

This review summarizes the data about synthetic approaches to fluorinated ruthenium metathesis

CHAPTER II RESULTS AND DISCUSSIONS

Introduction

Recent progress in development of new ruthenium-based metathesis catalysts connects mainly with the modification of N-heterocyclic carbene (NHC) ligand of commercially available Grubbs (G-II) and Hoveyda-Grubbs (HG-II) complexes to directly affect catalyst efficacy. For instance, the variation of electronic and steric properties of the substituents at nitrogen atoms, placed in vicinity to carbene center, can significantly alter the catalytic activity, stability and selectivity in many metathetic transformations.

On the other hand, the chemistry of fluorinated compounds is an area of tremendous expansion. The field of applications is impressively wide in scope and has the potential to concern all fields of life and material sciences. It is universally acknowledged that the presence of fluoroalkyl groups in a molecule profoundly modifies its physicochemical properties through concomitant alteration of its steric, electronic and lipophilic characteristics. This concerns in particular trifluoromethylated compounds, as CF3-group is one of the most lipophilic groups in organic chemistry, and has one of the highest electronegativity and steric hindrance.

In the field of ruthenium-alkylidene complexes, the steric and electronic impact of fluorine and fluoroalkyl groups on their catalytic properties has been mainly studied by usage of properly modified phosphine, styrene ligands, as well as by the replacement of one or two chlorine atoms at ruthenium, e.g. with perfluoroalkoxylates. However, the number of publications on metathesis catalysts decorated with fluorinated NHC ligands is extremely limited [START_REF] Fustero | Olefin Metathesis Reactions with Fluorinated Substrates, Catalysts, and Solvents[END_REF] . Therefore, the development of new efficient metathesis catalysts bearing NHC ligands modified with trifluoromethyl-containing functional groups is of great interest in modern organic and organometallic chemistry.

The main goal of the present thesis is to develop efficient methods for the preparation of new ruthenium carbene complexes with unsymmetrical trifluoromethyl substituted NHC ligands and to investigate their catalytic activity in intra-and intermolecular olefin metathesis. Due to the fact that the catalytic activity of ruthenium carbene complexes strongly depends on steric volume and electronic nature of substituents on nitrogen atoms of NHC ligand, a great attention of the researchers has been recently focused on unsymmetrical NHCs (uNHCs) as desymmetrization allows for rapid implementation of further fine-tuning. The introduction of chelation, bifunctionality, shielding effects, and chirality-transfer can influence the catalyst stability, reactivity, and selectivity, thus stimulating the search for new tailor-made systems including mono-and multidentate uNHC ligands.

Synthesis of ruthenium carbene complexes with unsymmetrical fluorine-containing N,N'-diarylimidazoline-2-ylidene ligands

Among known olefin metathesis catalysts the ruthenium carbene complexes bearing 4,5-dihydroimidazole-based NHC ligands with ortho-substituted N-aryl groups possess the highest activity. Therefore, we choose the synthetic strategy based on the initial preparation of unsymmetrical bisarylethylene diamine A followed by heterocyclization to imidazolinium salt B as the precursor of the corresponding carbene C (Figure 1).

Scheme 1

Since it was known from the literature that the increase of steric hindrance of the substituents at NHC nitrogen atoms could bring an enhanced stability to the corresponding ruthenium complex, improving often its performance, we were interested in preparation of unsymmetrical salts with bulky hexafluoroisopropylmethoxy group in ortho-position of N-aryl moiety. For this purpose analogous ortho-substituted aniline 7 (Scheme 2), formed via alkylation 2,4-dimethylaniline by hexafluoroacetone hydrate, was quantitatively transformed into benzoxazine 8 under treatment with chloroacetic acid chloride. After mild ring opening of 8 the same procedure as for 5 (Scheme 1) was used for the preparation of hydroxyl-containing diamine 10. To alkylate OH-function selectively, the diamine 10 was initially protected with two trifluoroacetic groups, which were removed after successful O-methylation by treatment of the trifluoroacetylated derivative 11 with potassium hydroxide to yield the unsymmetrical diamine 12.

Scheme 2

However, all our attempts to accomplish heterocyclization of 12 into the corresponding salt applying conventional methods have proved to be unsuccessful. Thus, the treatment of 12 with triethyl ortho-formate led to the formation of complicated mixture of products, from which the only formylated derivative 13 was isolated in poor yield (Scheme 3).

Taking into account the fact, that formamides are known decomposition products of NHCs, and precedents exists even for their inter-conversion in the case of less bulky mono-formamides 145 , an alternative approach to imidazolinium salt 14 has been developed based on intermolecular heterocyclization of mono-formamide 13.

Scheme 3

For this aim, the synthesis of compound 13 was optimized via formylation of diamine 12 by usage of acetic-formic mixed anhydride. The reaction selectively occurs at the more sterically accessible nitrogen atom and goes to completion for 15 min at room temperature in ether to afford mono-formylated derivative 13 (Scheme 4).

Scheme 4

Then we found, that the successive addition of stoichiometric amounts of triflic acid (TfOH) and triflic anhydride (Tf2O) to the formylated compound 13 provided conditions for Vilsmeyer-Haack reaction via covalent activation of amide group. The use of Hünig's base (DIPEA) has proved to be optimal for the final cyclization step to produce the desired imidazolinium triflate salt 14 in excellent yield (Scheme 5). Fortunately, the final fluorinated imidazolinium triflate 14 can be easily purified by single recrystallization from hexanes.

Scheme 5

With these new fluorinated uNHC salts in hand, we prepared the ruthenium complexes 15 and 16. The corresponding carbene were generated in situ by the treatment of starting salts 6 and 14 with potassium hexamethyldisilazide (KHMDS) in anhydrous toluene at 0 °C under argon atmosphere with subsequent addition of first generation commercially available RuCl2(PCy3)2(=CHPh) G-I and RuCl2(PCy3)(=CH(o-i PrO-C6H4) HG-I. As a rule, the ligand exchange required an additional stirring of the reaction mixture at room temperature for two hours or heating at 60 °C for 30 min. Purification by silica gel chromatography and further recrystallization from a DCM/n-pentane mixture afforded dark-brown (4) and dark-green (5), air stable solids in moderate yields (Scheme 6).

Scheme 6

Complexes 15a,b and 16a,b were completely characterized by NMR spectroscopy and elemental analysis. The NHC ligands of complexes 16a,b rotate fast on the NMR timescale and, therefore, only one signal is observed in the benzylidene region of the 1 H NMR spectra (around 16.5 ppm) for these phosphine-free complexes. In the case of phosphine-containing complex 15a a mixture of two rotational isomers (~2:1) is formed. It can be rationalized by different location of mesityl and fluorinated aryl rings above the benzylidene group due to possible π-π stacking interaction. In contrast, the sole carbene proton signal of 15b (20.2 ppm) is observed as the result of hindered rotation of NHC ligand due to anchoring effect of bulky ortho-substituent. 2D NMR (HMBC) experiment unambiguously evidences the location of the fluorinated aryl moiety above the benzylidene ring (cross peak between styrene ortho-H (7.33 ppm) and quaternary carbon (84.35 ppm) of (CF3)2C-OMe group (Figure 2). The presence of CF3 groups in the molecule gives a unique possibility both to control the progress of reactions and to get an additional information about the structural peculiarities of the compounds obtained by usage of 19 F NMR spectroscopy. For instance, in 19 F NMR spectra of para-substituted complex 15a one singlet at -70.24 ppm corresponds to two equivalent CF3 groups, whereas for the complex 15b bearing hexafluoroisopropylmethoxy group in ortho-position these groups become not equivalent due to hindered rotation of fluorinated aryl moiety around C-N bond that leads to the appearance of two individual singlets in the field of -63.57 and -68.96 ppm respectively (Figure 3). This situation is typical for other similar complexes also. In addition single crystals of good quality for X-ray analysis from complexes 16a,b were obtained (Figure 4).

16a 16b

The structures of complexes 16a and 16b were compared to that of the olefin metathesis catalyst RuCl2(bis(mesityl)imidazolinylidene)(ortho-isopropoxybenzylidene) HG-II (Table 1).

These three complexes crystallize in a monoclinic system. All bond lengths and angles are quite similar, which shows that the substitution has not a strong effect on the structures of the different complexes, especially around the metal center. The chelate (Ru-C(1)-C(3)-O) is almost planar and parallel to the plane of the five-membered NHC ring. The two chloride atoms are in trans-position with a Cl 1 -Ru-Cl 2 angle of 156-159°, in a plane, which is perpendicular to the bidentate isopropoxybenzylidene and NHC ligands. It can be noted that in the solid state, the fluorinated group in the Hoveyda type complex 16a is located at the opposite side of the benzylidene ligand, whereas for complex 16b, this group sits above the benzylidene ligand bringing more steric hindrance on the carbene side.

O-Ru-C(1)- C(3) 5.3(3) 3.2(3) 1.4(3)
The investigation of catalytic activity of complexes obtained will be discussed in chapter 2.6.

Synthesis of ruthenium carbene complexes with fluorine-containing mono-ortho-aryl substituents in NHC ligands

As known from the literature, the variation of the substitution pattern in N-aryl moieties of the NHC ligand led to extremely active catalysts for challenging transformations involving metathesis of hindered substrates. However, it is not always easy to predict how structural and electronic changes at the NHC can affect the catalyst activity. For example, the presence of bulky substituents finally (e,f) selective formylation at the more sterically accessible amino group using acetic-formic mixed anhydride followed by heterocyclization via the treatment with stoichiometric amounts of triflic acid (TfOH) and triflic anhydride (Tf2O) to give the target NHC precursors 26a and 26b in 85% and 83% yields, respectively (Scheme 8). The last two steps (e,f) were performed using a slightly modified procedure previously developed by us for sterically demanding fluorinated imidazolinium salts (see chapter I). It is noteworthy that all intermediates of this synthetic sequence were isolated in high yields by simple crystallization from common organic solvents without additional purification via column chromatography.

Scheme 9

The complexes obtained were fully characterized by NMR spectroscopy and elemental analysis. In 1 H NMR spectra of phosphine-containing 27a,b as well as phosphine-free 28a,b complexes measured at room temperature the absorptions of intrinsic benzylidene protons are observed around 19.6 ppm and 16.9 ppm, respectively, as two broad singlets in each case. The doubling of the signals for CF3-groups takes place in 19 F NMR spectra also. This phenomenon could be attributed to the existence of two rotamers due to hindered rotation of bulky fluorinated aryl group around C-N bond. These doublets come together at 60-80 °C under NMR experiment measured in d8-toluene, which supports the existence of rotamers. The 13 C NMR spectrum of the NHC at 60 °C displays a resonance at 290 and 216 ppm for the carbene (N-C-N) and benzylidene (Ru=C-H) carbons respectively, which are in the expected range for aryl-substituted imidazolylidenes.

A typical picture of 1 H NMR experiment measured at elevated temperature for the range of benzylidene proton is depicted on Figure 5. In addition, single crystals of good quality for X-ray analysis from complexes 28a,b (Figure 6) were obtained by slow diffusion of pentane into a concentrated dichloromethane solution.

28a 28b

Figure 6 2.4.

Synthesis of ruthenium carbene complexes with fluorinated N-alkyl-N-arylimidazoline-2-ylidene ligands

As it is well known, the increase of NHC ligand donating properties usually leads to enhanced stability of the resulting metal complexes that in turn can favorably affect the catalyst efficiency.

Taking into account this fact we have decided to synthesize unsymmetrical ruthenium carbene complexes with more donating alkyl substituent at one of the nitrogen atoms in the imidazoline-2-ylidene ligand.

For this purpose fluorinated anilide 3, which is easily available from commercial 2,6-dimethylaniline, hexafluoroacetone hydrate and chloroacetyl chloride (see Scheme 1), was used as starting material. Thus, it was found that its reaction with primary amines, such as tertbutylamine, iso-propylamine and cyclohexylamine, readily occurs at room temperature in excess of amine without any solvent and leads to completion after 1-3 days (TLC control) affording the corresponding aminoamides 29a-c in almost quantitative yields (Scheme 10). The subsequent reduction of the keto group in amides 29 can be effectively performed by usage of complex BH3SMe2 in toluene at 80 C to give good yields of diamines 30a-c. The latter undergo intramolecular cyclization under standard treatment with triethyl ortho-formate leading to the formation of the desired imidazolinium salts 31a-c.

Scheme 10

The salts obtained by this way were further utilized as precursors of the corresponding N-heterocyclic carbenes for the synthesis of the target ruthenium complexes 32a-c (Scheme 11).

As in the previous cases the carbenes were generated in situ by treatment of the starting salts 31a-c with potassium hexamethyldisilazide (KHMDS) in anhydrous toluene under argon atmosphere at 0 С and with subsequent addition of Hoveyda first generation complex HG-I to the reaction mixture. Usually, the reaction required slight heating for 30-40 min to complete the ligand exchange process (PCy3 for NHC). The resulting complexes 32a-c were isolated by means of column chromatography on silica gel as dark-green solids and fully characterized using NMR spectroscopy ( 1 H, [START_REF] Lam | Synthesis and Evaluation of Molybdenum and Tungsten Monoaryloxide Halide Alkylidene Complexes for Z-Selective Cross-Metathesis of Cyclooctene and Z-1,2-Dichloroethylene[END_REF] C, 19 F) and elemental analysis.

Scheme 11

As in other cases of phosphine free complexes, in 1 Besides that, the characteristic absorptions of carbenic atoms (N-C-N) are observed in [START_REF] Lam | Synthesis and Evaluation of Molybdenum and Tungsten Monoaryloxide Halide Alkylidene Complexes for Z-Selective Cross-Metathesis of Cyclooctene and Z-1,2-Dichloroethylene[END_REF] C NMR spectra around 306, 285 and 286 ppm for 32a, 32b and 32c, respectively.

As example, 1 H, 19 F and [START_REF] Lam | Synthesis and Evaluation of Molybdenum and Tungsten Monoaryloxide Halide Alkylidene Complexes for Z-Selective Cross-Metathesis of Cyclooctene and Z-1,2-Dichloroethylene[END_REF] C NMR-spectra of tert-butyl-containing complex 32a are depicted at Figures 7 and8, on which all intrinsic signals could be well identified. [START_REF] Lam | Synthesis and Evaluation of Molybdenum and Tungsten Monoaryloxide Halide Alkylidene Complexes for Z-Selective Cross-Metathesis of Cyclooctene and Z-1,2-Dichloroethylene[END_REF] C NMR-spectra of 32a in d6-benzene. 1 H NMR (400 MHz, C6D6) 19 F NMR (376 MHz, C6D6) [START_REF] Lam | Synthesis and Evaluation of Molybdenum and Tungsten Monoaryloxide Halide Alkylidene Complexes for Z-Selective Cross-Metathesis of Cyclooctene and Z-1,2-Dichloroethylene[END_REF] C NMR (101 MHz, C6D6)

N-C-N Ru=C-Ar CF3 C(CF3)2
Then we did several attempts to synthesize similar complexes comprising hexafluoroisopropylmethoxy group in ortho-position of N-aryl substituent in NHC ligand but failed. The synthetic sequence was interrupted at the stage of the keto group reduction of amide 34 (Scheme 12). In all cases the reaction unexpectedly led to the formation of O-demethylation products 35a-c in moderate yields.

Scheme 12

Probably, it could be rationalized by the possible formation of more favorable intermediate A under reaction conditions due to enhanced nucleophilicity of nitrogen atom substituted with more donating alkyl group to compare with the cases of N-aryl group, in which the demethylation process did not occur (e.g. see Scheme 8, step d). Therefore, our further synthetic attempts to prepare the corresponding imidazolinium salts were stopped.

Investigation of catalytic activity of complexes obtained

The

Scheme 14

The obtained complexes 41 and 42 were fully characterized by the modern physicochemical methods including X-ray analysis for compound 42 (Figure 9).

Figure 9

As a result, the catalytic activity of all synthesized new ruthenium complexes, depicted at

Figure 10

The kinetic experiments for all compounds were performed by taking the samples from the reaction mixture after a certain period of time suppressing the activity of the catalyst by addition to the mixture an excess of ethyl vinyl ether 147 .

The ring closing metathesis (RCM) of diethyl diallylmalonate (DEDAM) was selected as the first model reaction, which has been performed in standard for known carbene complexes conditions (Scheme 14).

Scheme 14

For a better perception the results obtained were divided for two parts depending on the catalyst type. The data of catalytic activity of phosphine-containing complexes 15, 27 and 41 are presented in Table 2 in comparison with the corresponding benchmark (G-II). The catalytic activities of phosphine-free complexes 16, 28, 32 and 42 along with benchmark HG-II are shown in Table 3. As can be seen from the table, almost all new complexes have exhibited high activity reaching the standard G-II level. The only exception is the complex 41 bearing symmetrical NHC ligand that demonstrates the positive impact of desymmetrization in the series of fluoroalkyl-containing ruthenium complexes.

In the case of phosphine-free complexes only 16a has reached a level of benchmark HG-II.

Meanwhile, both 16a and its ortho-fluoroalkyl analogue 16b have demonstrated a long initiation period before the catalytic systems operate efficiently (Table 3). Less sterically demanding complexes 28a,b comprising fluoroalkyl-containing mono-ortho-aryl substituents do not possess a latent period and exhibit seamless rate's acceleration reaching a maximum conversion of 92% within 4 hours. The symmetrical complex 42 as its phosphine-containing analogue 41 catalyzes this RCM reaction with lower rate.

N-Alkyl substituted complexes 32b,c have proved to be much less active. Notably, compound 32a bearing the more bulky tert-butyl group at nitrogen atom does not catalyze this process at all. Then, the catalytic activity of the synthesized complexes was investigated in cross metathesis (CM) reaction of allyl benzene with an excess of 1,3-diacetoxybut-2-ene. The reactions were performed at room temperature in methylene chloride with catalyst loading of 2.5 mol.% (Scheme 15). The data obtained were also separated in two different tables (3 and 4) according to the catalyst type.

Scheme 15

As result it was found that the complexes with PCy3 ligand 15, 27, and 41 exhibit reactivity similar to the commercially available catalyst G-II. In all cases equilibrium around 79-82% conversion can be reached within 30 min with closely related kinetic profiles (Table 4). The activity of phosphine-free complexes in cross metathesis reaction exceeded in some cases the activity of catalyst HG-II (Table 5). Thus, complexes 28a and 28b bearing mono-ortho-aryl substituent in NHC ligand have demonstrated unusual high initiation rate already in two minutes after start of the reaction, reaching 10% more conversion (83%) in comparison with the same value for the benchmark catalyst HG-II. The complexes 16a,b with more bulky NHC ligands have similar to HG-II kinetic profiles.

Only N-alkyl-containing complexes 32b,c as in the case of RCM reaction have demonstrated very low reactivity in CM; at that N-tert-butyl substituted complex 32a has proved to be absolutely inert in this reaction.

On the whole, as result of the study of new fluoroalkyl-containing carbene complexes, it was found that most of complexes obtained have exhibited high catalytic activity in tested reactions of intra-and intermolecular olefin metathesis. Their reactivity was comparable with commonly used in these processes second generation Grubbs and Hoveyda catalysts. In the case of new Hoveyda type catalysts with mono-ortho-aryl substituted NHC ligands their performance has seemed to be 2. New imidazolinium salts with fluoroalkyl-containing mono-ortho-aryl substituent at one of the nitrogen atom have been synthesized based on alkylation of para-toluidine and paraanisidine by hexafluoroacetone hydrate.

A convenient method for the preparation of new N-alky-N-arylimidazolinium salts has been

developed based on condensation of para-fluoroalkyl-containing chloroacetic anilide with iso-propyl-, cyclohexyl-and tert-butyl amines as a key step of the reaction sequence.

CHAPTER III EXPERIMENTAL PART

General remarks

Synthesis

Synthesis of 2-(4-amino-3,5-dimethylphenyl)-1,1,1,3,3,3-hexafluoropropan-2-ol (1).

A

Synthesis of 2-chloro-N-[4-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-2,6-dimethylphenyl]acetamide (3).

Chloroacetyl chloride (3.5 g, 31.0 mmol) was added dropwise to the solution of 2 (8.5 g, 28.2 mmol) and DMAP (4.48 g, 36.7 mmol) in 120 mL of anhydrous CH2Cl2 at 0 °C. The reaction mixture was stirred overnight at r.t.

Then, the mixture was concentrated to 30 mL under reduced pressure, treated with 5% HCl (100 mL), and extracted with CH2Cl2 (3 × 50 mL). Combined organic layers were washed with saturated solution of NaHCO3 (50 mL) and of water (50 mL) and dried over MgSO4. After solvent removal under vacuum, the crude acetylated intermediate was purified by column chromatography in a gradient manner using EtOAc/petroleum ether (1:4-1:2-1:1-1:0) as the eluent to yield 8.9 g of the corresponding chloroacetamide 3 as a white solid. Yiled: 84%. (5).

Synthesis of N 1 -[4-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-2,6-dimethylphenyl]-N 2 - mesitylethane-1,2-diamine
A mixture of 4 (9.8 g, 20.9 mmol) and mesitylamine (42.3 until ceasing of gas evolution. Then, a 5% solution (300 mL) of HCl was added and resulting mixture was extracted with EtOAc (2 × 120 mL). The aqueous layer was separated, treated with NaHCO3, and extracted with EtOAc (2 × 120 mL).

Combined organic layers were washed with a saturated solution of NaHCO3, dried over MgSO4, and concentrated under reduced pressure. The crude product was purified by column chromatography using EtOAc/petroleum (1:6) ether as eluent to yield 8.5 g of 5 as a colorless oil.

Yield: 93% (88% for 2 steps) 1 H NMR (400 MHz, Acetone-d6): δ 7.18 (s, 2H, HAr), 6.77 (s, 2H, HAr), 4.30 (br.s, 1H, NH), 3.52 (br.s, 1H, NH), 3.47 (s, 3H, OMe), 3.37 (t, 3 JH,H = 5.9 Hz, 2H, CH2), 3.12 (t, 3 (6).

Synthesis of 1-[4-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-2,6-dimethylphenyl]-3-mesityl- 4,5-dihydro-1H-imidazol-3-ium chloride
Concentrated HCl (10 mL, 120 mmol) was added to the solution of 5 (6 g, 13.0 mmol) in MeOH (100 mL) and stirred for 10 min.

The solution was evaporated under reduced pressure.

Synthesis of 2-(2-amino-3,5-dimethylphenyl)-1,1,1,3,3,3-hexafluoropropan-2-ol (7).

A mixture of 2,4-dimethylaniline (10.0 g, 82.6 mmol), hexafluoroacetone sesquihydrate (30 g, 153.8 mmol), and PTSA (200 mg, 1.1 mmol) was heated at 100 °C for 20 h. After cooling to r.t., water (50 mL) was added and the resulting mixture was extracted with EtOAc (3 × 30 mL). The combined organic layers were washed with H2O and brine and then dried over MgSO4.

The solvent was removed under reduced pressure, and the crude product was recrystallized from petroleum ether to give 21.9 g of 7 as a brown solid. Yield: 92%. mp 110-112 °C.

Synthesis of 2-(chloromethyl)-6,8-dimethyl-4,4-bis-(trifluoromethyl)-4H-benzo[d][1,3]oxazine (8). (isolated as intermediate in synthesis of 9).

Chloroacetyl chloride (0.21 g, 1.9 mmol) was added dropwise to the solution of 7 (0.

Synthesis of N-[2-(1,1,1,3,3,3-hexafluoro-2-hydroxypropan-2-yl)-4,6-dimethylphenyl]-2-iodoacetamide (9).

Chloroacetyl chloride (7.0 g, 62. Then, solvents were evaporated under reduced pressure, the residue was dissolved in MeOH (300 mL), and concentrated HCl (15 mL) was added to the solution. The mixture was stirred overnight.

Then, solvents were removed under reduced pressure and the residue was treated with a saturated solution of NaHCO3 (500 mL) and extracted with EtOAc (2 × 200 mL). Combined organic layers were washed with 200 mL of water, dried using MgSO4, filtered, and concentrated under low pressure. The residual dark brown solid was recrystallized from petroleum ether to afford 17.7 g of the corresponding chloroacetamide as a light brown solid. Yield: 93%.

Synthesis of 1,1,1,3,3,3-hexafluoro-2-(2-{[2-(mesitylamino)-ethyl]amino}-3,5-dimethylphenyl)-

propan-2-ol (10).

A mixture of 9 (12.5 g, 27.5 mmol) and mesitylamine (55.7 g, 412.0 mmol) was stirred at r.t. for 4 days. After reaction completion (TLC comtrol), the mixture was treated with a 10% solution of NaHCO3 (100 mL) and extracted with EtOAc (3 × 60 mL). Combined organic layers were washed with brine and water and then dried over MgSO4 and concentrated under reduced pressure. The excess of MesNH2 was removed at 70 °C/0.05 mmHg. The residual solid was recrystallized from petroleum ether to give 12.0 g of the corresponding adduct as a white solid.

Yield: 94%. (11).

Synthesis of 2,2,2-trifluoro-N-[2-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-4,6-dimethyl- phenyl]-N-[2-(2,2,2-trifluoro-N-mesitylacetamido)ethyl]acetamide
TFA (1.5 g, 13.4 mmol) and pyridine (1.1 g, 13.4 mmol) were added sequentially to the solution of 10 (3 g, 6.7 mmol) in CH2Cl2 (30 mL) at 0 °C. The reaction mixture was stirred at r.t. for 1 h, and then water (30 mL) was added to the mixture. The organic layer was separated; the aqueous layer was extracted with CH2Cl2 (2 × 20 mL). Combined organic layers were dried over MgSO4, filtered, and concentrated under reduced pressure. The crude product was recrystallized from petroleum ether to yield 4.0 g (6.3 mmol, 94%) of the corresponding protected diamine as a white solid. This compound (2.0 g, 3.2 mmol) was dissolved in dry DMF (25 mL). MeI (1.3 g, 9.5 mmol) and anhydrous K2CO3 (1.74 g, 12.6 mmol) were added, and the resulting solution was heated overnight at 80 °C. Then, after cooling to r.t., 20 mL of water was added to the mixture. The crude product was extracted with EtOAc (3 × 15 mL). Combined organic layers were dried over MgSO4, filtered, and concentrated under reduced pressure to afford 1.97 g of 11 as a white solid. Yield: 93%. mp 118-120 °C. 1 (12).

Synthesis of N 1 -[2-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-4,6-dimethylphenyl]-N 2 - mesitylethane-1,2-diamine
A mixture of 11 (1.97 g, 3.0 mmol), 18-crown-6 (5 mg, 0.02 mmol), and a solution of KOH (13 g, 230 mmol) in water (8 mL) was heated in DMSO (15 mL) at 130 °C for 1.5 h; then the reaction mixture was allowed to stir overnight at r.t. Water (30 mL) was added, and the crude product was extracted with EtOAc (3 × 20 mL). Combined organic layers were washed with 20 mL of water, dried over MgSO4, and concentrated. The product was purified by column chromatography using EtOAc/petroleum ether (1:20) as eluent to yield 1.05 g of 12 as a yellowish oil. Yield: 75%. (13).

Synthesis of N-(2-{[2-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-4,6-dimethylphenyl]- amino}ethyl)-N-mesitylformamide
Acetic formic anhydride (0.4 g, 4.54 mmol) was added dropwise to the solution of 12 (1.05 g, 2.27 mmol) in CH2Cl2 (20 mL). After homogenization, the reaction mixture was allowed to stir for 15 min at r.t. Then, 40 mL of water was added and the mixture was extracted with CH2Cl2 (2 × 30 mL). Combined organic layers were washed with a saturated solution of NaHCO3 and water, dried over MgSO4, filtered, and concentrated under reduced pressure. The crude product was purified by column chromatography using EtOAc/petroleum ether (1:4) as eluent to yield 1.03 g of 13 as a colorless oil. Yield: 92%. 1 H NMR (300 MHz, CDCl3): δ 8.02 (s, 1H, CHO), 7.03 (s, 1H, HAr), 6.95 (s, 3H, HAr), 5.06 (s, 1H, NH), 3.80 (t, 3 JH,H = 7.4 Hz, 2H, CH2), 3.43 (s, 3H, OMe), 3.13 (q, 3 (14).

Synthesis of 1-[2-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-4,6-dimethylphenyl]-3-mesityl- 4,5-dihydro-1H-imidazol-3-ium triflate
Triflic acid (0.2 g, 1.37 mmol) was added to the solution of 13 (0.67 g, 1.37 mmol) in toluene (30 mL), and the mixture was stirred at r.t.

for 15 min. Then, triflic anhydride (0.29 g, 1.37 mmol) was added, and the reaction mixture was heated at 65 °C for 1.5 h. DIPEA (0.53 g, 4.11 mmol) was added, and the reaction mixture was heated at 80 °C for another 1.5 h. After cooling to r.t., solvents were removed under reduced pressure, water (30 mL) was added and the mixture was extracted with CH2Cl2 (3 × 20 mL). The combined organic layers were dried using MgSO4, filtered, and concentrated under reduced pressure. The crude product was recrystallized from petroleum ether to give 0.84 g of 14 as a beige solid. Yield: 97%. General procedure for synthesis of Grubbs-type catalysts 15a and 15b.

In a flame-dried Schlenk flask, imidazolinium salt 6 or 14 (1.00 mmol) was mixed with 20 mL of anhydrous toluene. The resulting mixture was cooled to 0 °C and degassed three times, and then KHMDS (1.04 mL of 1 M solution in THF, 1.04 mmol) was added to the mixture under an argon atmosphere. The reaction mixture was stirred for 30 min at r.t.; then Grubbs' catalyst G-I (0.63 g, 0.82 mmol) was added and mixture was stirred for 2 h. During this time, the reaction mixture changed color from violet to red-brown. Once complete (TLC control), solvents were removed from the reaction mixture under reduced pressure, and the resulting substance was purified by column chromatography in a gradient manner using EtOAc/petroleum ether (1:8-1:3) as eluent under an argon atmosphere. The resulting solid was recrystallized from MeOH to yield 15 as a brown solid.

Benzylidene(dichloro){1-[4-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-2,6-dimethylphenyl]-

3-mesityl-4,5-dihydroimidazol-2-ylidene}(tricyclohexylphosphine)ruthenium(II) (15a).

Yield: 50%. Brown powder. 1 General procedure for synthesis of Hoveyda-type catalysts 16a and 16b.

Benzylidene(dichloro){1-(2-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-4,6-dimethylphenyl)- 3-mesityl-4,5-dihydroimidazol-2-ylidene}(tricyclohexylphosphine)ruthenium(II) (15b
In a flame-dried Schlenk flask, imidazolinium salt 6 or 14 (0.98 mmol) was mixed with 35 mL of anhydrous toluene. The resulting mixture was cooled to 0 °C and degassed three times; then KHMDS (1.25 mL of 1 M solution in THF, 1.25 mmol) was added to the mixture under an argon atmosphere. The reaction mixture was stirred for 30 min at r.t.; then Hoveyda catalyst HG-I (0.49 g, 0.82 mmol) was added and mixture was stirred for 40 min at 80 °C. During this time, the reaction mixture changed color from brown to green. Once complete, solvents were removed from the reaction mixture under reduced pressure, and the resulting substance was purified by column chromatography using EtOAc/petroleum ether (1:3) as eluent to yield Hoveyda-type catalyst as a green solid. Suitable for X-ray crystals of 16a and 16b were grown by slow diffusion of hexane vapors in CH2Cl2 solution.

Dichloro{1-[4-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-2,6-dimethylphenyl]-3-mesityl-4,5-dihydroimidazol-2-ylidene}(2-isopropoxybenzylidene)ruthenium(II) (16a).

Yield: 46%. Dark-brown powder.

Dichloro{1-[2-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-4,6-dimethylphenyl]-3-mesityl- 4,5-dihydroimidazol-2-ylidene}(2-isopropoxybenzylidene)ruthenium(II) (16b).
Yield: 46%. Dark-brown powder.

General procedure for synthesis of 17.

A mixture of 6-methylaniline or 6-methoxyaniline (46.7 mmol), hexafluoroacetone sesquihydrate (18.6 g, 112.1 mmol), and PTSA (100 mg, 0.5 mmol) was heated at 100 °C for 20 h. After cooling to r.t., water (50 mL) was added and a resulting mixture was extracted with EtOAc (3 × 30 mL).

The combined organic layers were washed with H2O and brine and then dried over MgSO4. The solvent was removed under reduced pressure, and the resulting solid was recrystallized from petroleum ether to yield a dark solid.

2-(2-Amino-5-methylphenyl)-1,1,1,3,3,3-hexafluoropropan-2-ol (17a).

Yield: 94%. Brown solid. mp 110-113 °C; 1 H NMR (300 MHz, CDCl3) δ 7.37 (s, 1H, HAr), 7.16 (d, 3 JH,H= 8.0 Hz, 1H, HAr), 6.97 (d, 3 General procedure for synthesis of 18.

To a mixture of aniline 17 (20 mmol) in 60 mL of water concentrated sulfuric acid (10.7 mL, 200 mmol) was slowly added. The resulting mixture was cooled to 0 °C and solution of NaNO2 (1.59 g, 23.0 mmol) in 6 mL of water was added dropwise and reaction mixture was stirred in an ice bath for 30 min. Then solution of NaN3 (1.56 g, 24 mmol) in 6 mL of water was added dropwise.

After full addition, the reaction mixture was allowed to stir at r.t. for 3 h. Then the reaction mixture was extracted with EtOAc (3 × 20 mL). Combined organic layer was washed with brine (20 mL), dried over MgSO4 and concentrated under reduced pressure. The crude product was purified by flash chromatography using EtOAc/petroleum ether (1:3) as eluent to yield yellowish crystals.

2-(2-Azido-5-methylphenyl)-1,1,1,3,3,3-hexafluoropropan-2-ol (18a).

Yield: 95%. mp 64-65 °C; 1 H NMR (400 MHz, CDCl3) δ 7.44 (s, 1H, HAr), 7.33 (d, 3 JH,H= 8.2 Hz, 1H, HAr), 7.16 (d, 3 General procedure for synthesis of 21.

Aniline 20 (10.6 mmol) was added to 6 mL of glacial acetic acid in a round-bottomed flask followed by chloroacetyl chloride (870 μL, 10.9 mmol) and 10.4 mL of half-saturated aqueous sodium acetate. Precipitation of the amide was observed in 10 min. The product is stirred thoroughly with 10 mL of cold water and isolated by filtration. Solid product was dissolved in EtOAc and washed with saturated aqueous NaHCO3 and brine, dried above MgSO4. Then solvent was removed under reduced pressure, resulting solid residue was recrystallized in petroleum ether to yield a white solid.

N 1 -[2-(1,1,1,3,3,3-Hexafluoro-2-methoxypropan-2-yl)-4-methoxyphenyl]-N 2 -mesitylethane-1,2- diamine (24b).
Yield: 72%; mp 56-57 °C; 1 H NMR (400 MHz, CDCl3) δ 6.97 (d, 3 JH,H =8.9 Hz, 1H, HAr), 6.95 (s, 1H, HAr), 6.86 (s, 2H, HAr), 6.76 (d, 3 General procedure for synthesis of Grubbs-type catalysts 27.

In catalyst first generation HG-I (0.20 g, 0.30 mmol) was added and mixture was stirred for 40 min at 80 °C. During this time, the reaction mixture changed color from brown to dark green. Once complete, solvents were removed from the reaction mixture under reduced pressure, and the resulting substance was purified by column chromatography using EtOAc/petroleum ether (1:3) as eluent to yield Hoveyda-type catalyst as a green solid. Suitable for X-ray crystals of 28 were grown by slow diffusion of hexane vapors in CH2Cl2 solution.

Dichloro{1 General procedure for synthesis of diamines 30.

Aminoacetamide 29 (2.9 mmol) was dissolved in anhydrous toluene (18 mL), then BH3•SMe2 (6.5 mL of 2 M solution THF, 13.0 mmol) was dissolved dropwise at room temperature under argon atmosphere. The resulting mixture was heated at 80 °С for 8 hours. After cooling to r.t., MeOH was slowly added until ceasing of gas evolution. Then, a 10% solution (20 mL) of HCl was added and resulting mixture was extracted with EtOAc (2 × 30 mL). The aqueous layer was separated, treated with NaHCO3, and also extracted with EtOAc (2 × 30 mL). Combined organic layers were washed with a saturated solution of NaHCO3, dried over MgSO4, and concentrated under reduced pressure. 3 JH,H = 5.9 Hz, NCH(sH3)2), 6H, 1.56 (d, 3 (39).

N 1 -tert-Butyl-N 2 -[4-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-2,6-dimethylphenyl]ethane- 1,2-diamine (30a
taking the probes (~0.4 mL) from the reaction mixture. The reaction was quenched using excess of ethyl vinyl ether (0.5 mL). The conversion to CM product was determined by GC. En catalyse homogène, les catalyseurs de métathèse des oléfines les plus performants ont été développés à partir de complexes bien définis du ruthenium, du molybdène et du tungstène portant un site métal-carbène réactif. Parmi la variété de catalyseurs de métathèse obtenus à ce jour, les catalyseurs à base de ruthénium de type Grubbs (Figure 1) sont très populaires en raison de leur grande stabilité à l'air et à l'humidité, leur tolérance aux groupements fonctionnels (acides carboxyliques, alcools, cétones,…) qui leur permet de garder une bonne réactivité vis-à-vis des doubles liaisons dans ces conditions. Depuis 1992, quand les premiers catalyseurs bien définis du ruthénium ont été décrits, de nombreuses modifications ont été apportées aux structures de base. Malgré les énormes progrès réalisés durant les dernières décennies, la synthèse de nouveaux catalyseurs plus efficaces et sélectifs présente toujours un intérêt majeur. Parallèlement à la métathèse des alcènes, la chimie des composés fluorés connait une croissance rapide. En raison des propriétés spécifiques de l'atome de fluor telles que sa grande électronégativité, sa faible taille et polarisabilité, son aptitude à former des liaisons hydrogène et à coordonner des métaux de transition et de la forte énergie de la liaison C-F, les dérivés fluorés présentent des propriétés inhabituelles par rapport à leurs analogues non fluorés. Jusqu'à maintenant, seulement quelques catalyseurs de métathèse des olefins porteurs de ligands fluorés ont été décrits. Les propriétés de ligands fluorés préalablement énumérées pourraient avoir une influence notable sur les propriétés catalytiques de complexes du ruthénium. L'objectif principal du travail est le développement de méthodes efficaces pour la synthèse d'une série de nouveaux sels d'imidazolinium non symétriques, précurseurs de ligands carbéniques contenant le groupement encombrant hexafluoroisopropoxy, ainsi que la préparation des catalyseurs de type Grubbs et Hoveyda correspondants et l'évaluation de leurs propriétés catalytiques dans des réactions de fermeture de cycle par métathèse et de mlétathèse croisée (Figure 2).

Nouveaux

1.6.

Autre ligand de type L fluorés 1.7.

Ligands de type X fluorés 1.8. Conclusions Cette revue rassemble les données sur les approches synthétiques des catalyseurs à base de ruthénium à ligands fluorés. Dans la plupart des cas le choix des groupements fluorés a pour but de diminuer la densité électronique sur le centre métallique pour favoriser la formation de l'intermédiaire ruthénacyclobutane. L'introduction des groupements contenant du fluor peut apporter de meilleures solubilités, en aprticulier dans les métathèses de polymérisation, résoudre des problèmes de séparation et de récupération en utilisant des systèmes biphasiques. Des interactions directes Ru---F ont conduit à des activités catalytiques exacerbées. Cependant il apparaît peu d'information sur les catalyseurs porteurs de ligands NHC fluorés non symétriques.

2.2.

Synthèse de complexes du ruthenium à ligand N,N'-diarylimidazolin-2-ylidène fluoré non symétrique La stratégie de synthèse mise en oeuvre est basée sur la préparation initiale de la diamine non symétrique A suivie de l'hétérocyclisation en sel d'imidazolinium B, précurseur du carbène C (Figure 4). A partir de ces nouveaux précurseurs de carbènes N-hétérocycliques non symétriques, les complexes du ruthenium 15 et 16 ont été préparés. Les carbènes ont été générés in situ par traitement des sels 6 et 14 avec KHMDS dans du toluène anhydre à 0 °C sous atmosphere d'argon, puis les complexes de première génération RuCl2(PCy3)2(=CHPh) G-I et RuCl2(PCy3)(=CH(o-i PrO-C6H4) HG-I ont été additionnés. L'échange de ligand nécessite une agitation à température ambiante pendant deux heures ou un chauffage à 60 °C pendant 30 minutes. Les purifications sur gel de silice et recristallisation dans un mélange dichlorométhane/n-pentane conduisent aux complexes brun foncé (15) et vert foné (16) (Schéma 4). La fermeture du diallylmalonate de diéthyle par métathèse a été choisie comme réaction modèle (Schéma 11).

Schéma 11

La réaction de métathèse croisée qui a été sélectionnée met en jeu l'allylbenzène et le 1,3-diacetoxybut-2-ène (Schéma 12).

Schéma 12

Les comparaisons des activités ont été réalisées à partir des courbes cinétiques obtenues dans les expériences avec chacun des catalyseurs testés.

La plupart des complexes synthétisés ont de bonnes activités catalytiques en fermeture de cycle à partir du diallylmalonate d'éthyle et en métathèse croisée de l'allylbenzène avec le 1,3-diacetoxybut-2-ene. Leurs performances sont comparables à celles des catalyseurs de Grubbs et Hoveyda de seconde génération, avec toutefois quelques différences dans les étapes d'initiation. En particulier, il a été montré que les catalyseurs de type Hoveyda porteurs de ligands monosubstitués par un groupement fluoroalkyle en position ortho d'un des substituant N-aryle présentent une initiation très rapide dans les réactions de métathèse croisée. Au contraire, les complexes porteurs d'un groupement donneur alkyle ont montré une activité catalytique très faible, comme par exemple le complexe porteur d'un ligand (tert-butyl)NHC qui s'est révélé inerte à la fois en fermeture de cycle et métathèse croisée.

Les complexes porteurs d'un ligand NHC symétrique avec deux groupes hexafluoroisopropylmethoxy ont des activités catalytiques nettement inférieures à leurs homologues non symétriques, révélant ainsi la forte influence de l'absence de symétrie du ligand carbène NHC dans l'activité catalytique des complexes.

Conclusion générale

1.

De nouvelles familles de sels d'imidazolinium non symétriques porteurs du groupement hexafluoroisopropylmethoxy en position para-ou ortho d'un substituant N-aryle ont été préparées par de nouvelles méthodologies efficaces.

2.

Ces sels d'imidazolinium sont de bons précurseurs de carbènes N-hétérocycliques. En conséquence, une voie d'accès à des complexes du ruthénium porteurs d'un ligand N-hétérocyclique non symétrique a été développée. La méthode utilisée implique la deprotonation du sel d'imidazolinium par KHMDS suivie de l'échange du ligand phosphine des complexes de première generation de type Grubbs et Hoveyda-Grubbs.

3.

L'activité des nouveaux catalyseurs à ligands non symétriques a été évaluée dans des réactions modèles classiques de métathèse d'oléfines intra-et inter-moléculaire. La plupart de ces complexes du ruthénium présentant deux substituants purement aromatiques sont actifs en cyclisation du diallylmalonate de diéthyle et en métathèse croisée de l'allylbenzène avec le 1,3-diacetoxybut-2-ene, avec des performances comparables à celles des catalyseurs de deuxième génération de Grubbs et de Hoveyda-Grubbs.

4.

Au contraire, les complexes porteurs d'un groupement donneur N-alkyle ont montré une activité catalytique très faible. De même, les complexes porteurs d'un ligand NHC symétrique avec deux groupes hexafluoroisopropylmethoxy ont des activités catalytiques nettement inférieures à leurs homologues non symétriques, révélant ainsi la forte influence de l'absence de symétrie du ligand carbène NHC dans l'activité catalytique des complexes.

Figure 1 .

 1 Figure 1. The most common ruthenium metathesis catalysts: First-generation Grubbs catalyst (G-I), second-generation Grubbs catalyst (G-II), second-generation Hoveyda-Grubbs catalyst (HG-II).

Figure 2 .

 2 Figure 2. General structures of synthesized and tested catalysts in this work.

Figure 3 .

 3 Figure 3. General structural modifications of Grubbs-types catalysts.

Figure 4 .

 4 Figure 4. Complexes 2.

Scheme 8 .

 8 Scheme 8. Synthesis of complexes 4-7.

Scheme 9 .

 9 Scheme 9. Synthesis of complexes 8.

Figure 5 .Scheme 14 .Scheme 15 .

 51415 Figure 5. Complexes 15a and 15b.

Figure 6 .

 6 Figure 6. Synthesis of complexes 21.

Scheme 20 .Scheme 21 .Scheme 22 .Scheme 23 .

 20212223 Scheme 20. Synthesis of complex 33.Hoveyda-type catalysts with fluorine-and trifluoromethyl-containing arylidenes were described by S. Blechert[START_REF] Zaja | Ruthenium Olefin Metathesis Catalysts with Modified Styrene Ethers: Influence of Steric and Electronic Effects[END_REF] . Catalysts 34-36 were synthesized from fluorinated styrenes via ligand exchange reaction with commercially available G-I and G-II complexes (Scheme 21). Fluorinated firstgeneration catalysts showed higher activity then HG-I, whereas activity of second-generation catalysts was almost similar to HG-II.

Scheme 27 .

 27 Scheme 27. Synthesis of catalysts 45. Series of trifluoroacetamide-containing Hoveyda-type catalysts (Scheme 36) was described by S. Nolan, M. Mauduit et al. The corresponding styrene 46a was synthesized by acylation of 4isopropoxy-3-vinylaniline with trifluoroacetic anhydride. The catalysts 47 and 48 (Scheme 28)

Scheme 28 .

 28 Scheme 28. Synthesis of complexes 47-49.

Figure 7 .

 7 Figure 7. Catalysts 47a@SiO2 and 48a@SiO2.

Figure 8 .

 8 Figure 8. X-ray structure of complex 55.

Figure 9 .

 9 Figure 9. Complexes 71 and 72.

Scheme 43 .

 43 Scheme 43. Mechanism of indenylidene complex 74 formation.

2 . 53 .

 253 Scheme 53. Synthesis of complex 84.

Figure 10 . 87 .

 1087 Figure 10. Complex 87.In 2006-2012 J. Gladysz and co-workers published a series of publications that described second generation Grubbs-type catalysts 108 (Scheme 56), containing fluorous phosphine ligands 101 . Synthesis of fluorous phosphines for these catalysts has been described by their group in earlier contribution102 . The introduction of fluorous tag was carried out in two steps: on the first step PH3 was added to corresponding perfluoroalkylethylene in presence of radical initiator azobisisobutyronitrile (AIBN). This step yields the mixture of target compound (~90%) with primary and secondary phosphines PHx(CH2CH2(CF2)nCF3)3-x (x = 1,2; n = 5,7,9). On the second step addition was carried out in presence of less active initiator 1,1'-azobis-(cyclohexanecarbonitrile) (VAZO) to prevent polymerization. All the resulting phosphines 88 demonstrated very high fluorophilicity with partition coefficients between PFMC and toluene Pi(FBS) > 80 (Table3). Catalysts 89 were synthesized by ligand exchange of G-III in

  Tris(p-fluorophenyl)phosphine-(90a) and tris[p-(trifluoromethyl)phenyl]phosphine-containing (90b) indenylidene catalysts were obtained by S. Nolan with co-workers 105 . These complexes were synthesized from the pyridine containing indenylidene precursor M31 (Scheme 57). Activity of catalysts 90a and 90b were tested in a scope of substrates for RCM, RCEYM, RRM and CM. In most of cases the catalyst 90b demonstrated better activity, then corresponding non-fluorinated one (M20).

Scheme 57 .

 57 Scheme 57. Synthesis of complexes 90.

Figure 11 .

 11 Figure 11. Catalysts 98-103.

MolScheme 63 .

 63 Scheme 63. Synthesis of catalyst 104.

Figure 12 .

 12 Figure 12. Catalysts 105.

Figure 13 .Scheme 64 .

 1364 Figure 13. Complexes 106 and 107. In 2007 K. Grela, M. Mauduit et al. described the catalyst with chelating carboxylate group 108 (Scheme 64) that demonstrated a latent properties. Thus, it was inactive in RCM at room temperature and showed significant activity at heating or in presence of acids 133 . Catalysts 109a-c were prepared in situ, however fluorinated ones 109b and 109c demonstrated lower activity than 109a.

Scheme 66 .Scheme 67 .Scheme 68 .Scheme 69 .Scheme 70 .

 6667686970 Scheme 66. Synthesis of complexes 111. D. Fogg et al. used the third generation Grubbs complex for the preparation of new catalysts with fluorinated X-type ligands. The method involved the treatment of G-III with thallium perfluorophenoxide (Scheme 67)135 . The resulting complex 112 exhibited high activity in RCM of DEDAM even at low catalyst loading (0.05 mol. %). In addition 112 showed good activity in RCM to form medium-size cycles 136 .

Figure 14 .

 14 Figure 14. Complexes 118-120.

Figure 15 .

 15 Figure 15. Synthesis of complex 121.A series of other fluorophilic catalysts 122a-c and 123a,b, containing chiral racemic perfluorooxaalkanoate ligands (Figure16), has been described last year 140 . These complexes were tested in benchmark RCM reactions. Catalysts 123b and 123b showed the highest activity due to electrophilicity along with low steric hindered of 2-fluoro-2-(perfluoropropoxy)acetate ligands.

Figure 16 .

 16 Figure 16. Complexes 122 and 123.

  catalysts and their use in metathetic transformations. In most of cases, choice of fluorinated ligands connects with attempt to reduce electronic density at carbene center in order to promote the formation of key ruthenacyclobutene intermediate at the first step of catalytic cycle. It can be achieved by the substitution of L-or X-type ligands for strong electron-withdrawing fluorine or fluoroalkyl groups. Moreover, the introduction of fluorine-containing groups could provide for better solubility, particularly in metatheses of polymerization, as well as to solve catalyst separation or recovery problems via fluorous biphasic systems. In some cases, an additional Ru-F interaction was shown to be crucial for enhanced catalytic activity. However, to the best of our knowledge there are only few examples of ruthenium carbene complexes with unsymmetrical fluorinated NHC ligands up to date. The construction of such catalytic system could promote the creation of more selective metathesis processes. Therefore, the development of efficient synthetic approaches to ruthenium catalysts containing bulky fluorinated groups in asymmetric NHCs is of great current interest.

N-

  Heterocyclic carbenes (NHCs) have found widespread applications as important auxiliary ligands in modern organometallic and coordination chemistry. Their unique steric and electronic properties, such as high σ-basicity and low -acidity, have made possible the development of effective metal catalysts for various applications with the most outstanding examples in the field of ruthenium-catalyzed olefin metathesis.

Figure 1 First

 1 Figure 1

  (a) HFA•1.5 H2O, p-TSA (1 mol%), 100 °C, 95%; (b) PhCHO, toluene, 110 °C; (c) MeI, K2CO3, MeCN; 70 °C then HCl/H2O, rt; 72% for 2 steps; (d) ClCH2C(O)Cl, DMAP, CH2Cl2, rt; (e) NaI, acetone, rt; (f) MesNH2 (15-fold excess), rt; (g) BH3•SMe2, THF, 88% for 2 steps; (h) MeOH/HCl, rt, then HC(OEt)3, 100 °C, 60%. HFA = hexafluoroacetone; p-TSA = p-tolylsulphonic acid, DMAP = dimethylaminopyridine.

  (a) HFA•1.5 H2O, p-TSA (1 mol. %), 100 °C, 92%; (b) ClCH2C(O)Cl, DMAP, CH2Cl2, rt; (c) HCl/MeOH, rt; (d) NaI, acetone, rt; 79% for 3 stages; (e) MesNH2 (15-fold excess), rt; (f) BH3•SMe2, THF, 75% for 2 stages; (g) TFAA/Py, CH2Cl2, rt; (h) MeI, K2CO3, DMF; 93% for 2 stages; (i) KOH, 18-crown-6, DMSO/H2O, 130 °C, 75%.

Figure 2 .

 2 Figure 2. 2D NMR spectra (HMBC) of 15b.

Figure 3 .

 3 Figure 3. 19 F NMR spectra of 15a (а) and 15b (b).

7

 7 Scheme 7

Figure 5 .

 5 Figure 5. 1 H NMR-spectra of 28a (range for benzylidene proton) measured at different temperature.

  H NMR spectra of all compounds the signals of intrinsic benzylidene protons (Ru=C-H) are observed in the range 16.5-17.1 ppm and correspond to the signals of carbon atoms (Ru=C-H) around 208-209 ppm in 13 C NMR spectra.

Figure 7 .

 7 Figure 7. 1 H and 19 F NMR-spectra of 32a in d6-benzene.

Figure 8 .

 8 Figure8.[START_REF] Lam | Synthesis and Evaluation of Molybdenum and Tungsten Monoaryloxide Halide Alkylidene Complexes for Z-Selective Cross-Metathesis of Cyclooctene and Z-1,2-Dichloroethylene[END_REF] C NMR-spectra of 32a in d6-benzene.

  influence of structural and electronic peculiarities of fluorinated unsymmetrical NHC ligand on catalytic activity of new ruthenium carbene complexes was investigated on classical model reactions of intra-and intermolecular olefin metathesis. The commonly used commercially available Grubbs (G-II) and Hoveyda (HG-II) second generation catalysts were selected as the standards of comparison. Because of the latter have in their structure the symmetrical N,N-(bis)mesitylimidazoline-2ylidene ligands we were interested in additional determination how the desymmetrization factor can influence on the new catalysts reactivity. For these purposes the symmetrical ruthenium complexes bearing two hexafluoroisopropylmethoxy groups in para-position of N-aryl substituents were specially synthesized. So, a readily available diamine 36 was used as the starting compound (Scheme 13). It was found that its treatment with the excess of hexafluoroacetone hydrate led to the formation of product 37 in good yield as a result of double alkylation upon two free para-positions of aromatic core. Further synthetic sequence included: (b) the trifluoroacetylation of two secondary amino groups with trifluoroacetic anhydride; (c,d) selective O-methylation/deprotection to give symmetrical diamine 39; (e) intramolecular heterocyclization of the latter into the corresponding NHC precursor 40 under heating in excess of triethyl ortho-formate. The target complexes 41 and 42 were prepared by the same manner as in previous cases using the ligand exchange reaction with phosphine-containing complexes G-I and HG-I (steps f and g, respectively).

( a )

 a HFA•1.5H2O, p-TSA (1 мол.%), 100°C, 84%; (b) TFAA/Py, Et2O, 1 h, rt; (c) MeI, K2CO3, DMFA, 1.5 h, 80ºC; (d) KOH, 18-crown-6, DMSO/H2O, 1.5h, 130°C; (e) MeOH/HCl, rt, then HC(OEt)3, 100°C; (f) KHMDS, toluene, G-I, rt, 2 h; (g) KHMDS, toluene, HG-I, 60°C, 1 h.

Figure 10 ,

 10 Figure 10, was investigated and compared with activity of commercially available NHCcontaining G-II and HG-II complexes (see p. 3).

Diagram 1 .

 1 even higher in comparison to benchmark catalyst HG-II. Moreover, it was established the influence of structural and electronic peculiarities of fluorinated unsymmetrical NHCs on the initiation rate of the corresponding Ru-complexes, conversion of the starting olefins as well as the yield of the final metathesis products. Below we selected the most representative examples of kinetic profiles clearly reflecting the result of structural modifications made in the frame of the present work. The unsymmetrical complexes of G-II type have proved to be the most active among the synthesized ones in RCM of DEDAM. As shown on the diagrams 1 the kinetic profile of 15b is very close to commercial G-II catalyst. The initiation rate of complex 27b is higher than for G-II. The maximum conversion for both 15b and 27b is reached within 30 min. The symmetrical complex 41 is less active in this reaction. Activity of G-II type complexes in RCM. The unsymmetrical phosphine-free complexes of HG-II type have demonstrated better catalytic activity in CM reaction of allyl benzene with excess of 1,3-diacetoxybut-2-ene. Thus, complexes 28a and 28b have unusual high initiation rate reaching 10% more conversion in comparison with the benchmark catalyst HG-II. The N-isopropyl-containing complexes 32b have displayed very low reactivity in this metathetic transformation (Diagram 2).

Diagram 2 . 1 .

 21 Activity of HG-II type complexes in CM. The results obtained give more insight in performance of unsymmetrical ruthenium carbene complexes and can open the door in the design of more selective catalysts for challenging metathesis transformation, e.g. such as CM and ROMP. An efficient approach to a new family of unsymmetrical 1,3-bis(aryl)-4,5dihydroimidazolium salts comprising bulky hexafluoroisopropylmethoxy group in para-or ortho-position in one of the N-aryl substituents has been developed. The introduction of fluoroalkyl substituent in aromatic core has been accomplished by means of alkylation reaction of the corresponding 2,6-or 2,4-dimethylanilines with commercially available hexafluoroacetone hydrate under PTSA-catalysis. The further construction of imidazoline ring included as a key step the heterocyclization of the corresponding unsymmetrical ethylene diamine by the treatment with triethyl ortho-formate or by modified Vilsmeyer-Haack reaction.

4 . 6 . 7 .

 467 It was found that imidazolinium salts obtained could be effectively acted as the corresponding NHC precursors. Consequently, an efficient access to a series of new ruthenium carbene complexes with unsymmetrical NHC ligands has been developed. The method involves in situ generation of the carbene via treatment of the starting salts with potassium hexamethyldisilazide and subsequent ligand exchange reaction with PCy3-containing first generation Grubbs and Hoveyda complexes.5. The catalytic activity of the complexes obtained has been investigated on classical modelreactions of intra-and intermolecular olefin metathesis. As a result, it was found that most of the synthesized complexes have exhibited high activity in cyclization of diethyl diallylmalonate and in cross metathesis of allyl benzene with 1,3-diacetoxybut-2-ene. Their performance has proved to be comparable with commonly used second generation Grubbs and Hoveyda catalysts. Structural and electronic impact of fluorinated unsymmetrical NHC on reactivity of new ruthenium complexes has been studied. In particular, it was revealed that Hoveyda type catalysts with mono-ortho-aryl substituted NHC ligands have demonstrated very high initiation rate in CM reaction to reach 10% more conversion in comparison with benchmark catalysts. At the same time, catalysts with more donating N-alkyl NHCs have displayed low activity; for instance, the N-tert-butyl substituted complex has proved to be absolutely inert both in RCM and CM reactions. To establish the influence of desymmetrization factor on catalytic activity of fluorinecontaining complexes the symmetrical ruthenium carbene complexes bearing NHC ligands with two hexafluoroisopropylmethoxy group in para-positions of N-aryl moieties have been specially synthesized. It has been established that they are significantly inferior in reactivity to their asymmetric counterparts.

3 ×

 3 6 mmol) was added dropwise to the solution of 7 (15 g, 52.2 mmol) and DMAP (6.4 g, 52.2 mmol) in 200 mL of anhydrous CH2Cl2 at 0 °C and stirred overnight at r.t. The reaction mixture was treated with 5% HCl (150 mL) and extracted with CH2Cl2 (60 mL). Combined organic layers were washed with 60 mL of water and dried over MgSO4.

  a flame-dried Schlenk flask, imidazolinium salt 26 (0.49 mmol) was mixed with 20 mL of anhydrous toluene. The resulting mixture was cooled to 0 °C and degassed three times, and then KHMDS (1 mL of 0.5 M solution in toluene, 0.50 mmol) was added to the mixture under an argon atmosphere. The reaction mixture was stirred for 30 min at r.t.; then Grubbs catalyst G-I (0.33 g, 0.40 mmol) was added and mixture was stirred for 2 h. During this time, the reaction mixture changed color from violet to red-brown. Once complete (TLC control), solvents were removed from the reaction mixture under reduced pressure, and the resulting substance was purified by column chromatography in a gradient manner using EtOAc/petroleum ether (1:8-1:3) as eluent under an argon atmosphere. The resulting solid was recrystallized from MeOH to yield 27 as a brown solid.Benzylidene(dichloro){1-[2-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-4-methylphenyl]-3mesityl-4,5-dihydroimidazol-2-ylidene}(tricyclohexylphosphine)ruthenium(II) (27a).

Schéma 1 .

 1 catalyseurs de métathèse des oléfines à ligands carbènes N-hétérocycliques fluorés: Synthèse et activité catalytique Résumé La préparation efficace d'une nouvelle famille de sels de 1,3-bis(aryl)-4,5-dihydroimidazolium non symétriques comprenant un groupement encombrant hexafluoroisopropylmethoxy en position para-ou ortho-sur l'un des substituants N-aryle a été développée. De nouveaux sels d'imidazolium contenant un substituant fluoroalkyle en position ortho d'un des substituant aryle ont aussi été synthétisés. Ces sels sont d'excellents précurseurs de carbènes N-hétérocycliques qui ont permis l'accès efficace à une série de nouveaux complexes carbéniques du ruthénium à ligands NHC non symétriques. La méthode repose sur la génération in situ du carbène par traitement des sels d'imidazolium avec le potassium hexamethyldisilazide suivie d'un échange du ligand tricyclohexylphosphine à partir des complexes de Grubbs et Hoveyda de première génération. L'activité de ces nouveaux complexes a été étudiée sur des réactions modèles intra-et intermoléculaires de métathèse des oléfines. Il a été montré que la plupart des complexes synthétisés ont de bonnes activités catalytiques en fermeture de cycle à partir du diallylmalonate d'éthyle et en métathèse croisée de l'allylbenzène avec le 1,3-diacetoxybut-2-ene. Leurs performances sont comparables à celles des catalyseurs de Grubbs et Hoveyda de seconde génération, avec toutefois quelques différences dans les étapes d'initiation. Les effets structuraux et électroniques des ligands NHC non symétriques sur la réactivité des nouveaux complexes du ruthénium ont été étudiés. En particulier, il a été montré que les catalyseurs de type Hoveyda porteurs de ligands monosubstitués par un groupement fluoroalkyle en position ortho d'un des substituant N-aryle présentent une initiation très rapide dans les réactions de métathèse croisée. Au contraire, les complexes porteurs d'un groupement donneur alkyle ont montré une activité catalytique très faible, comme par exemple le complexe porteur d'un ligand (tert-butyl)NHC qui s'est révélé inerte à la fois en fermeture de cycle et métathèse croisée.Les complexes porteurs d'un ligand NHC symétrique avec deux groupes hexafluoroisopropylmethoxy ont des activités catalytiques nettement inférieures à leurs homologues non symétriques, révélant ainsi la forte influence de l'absence de symétrie du ligand carbène NHC dans l'activité catalytique des complexes.Mots-clésCarbènes N-hétérocycliquesCarbènes fluorés Catalyseurs de métathèse des oléfinesFermeture de cycle par métathèse Métathèse croiséeIntroduction généraleLa métathèse des oléfines est une réaction de redistribution des substitutents des oléfines par scission et génération d'une nouvelle oléfine (Schéma 1). Schéma général de la métathèse des oléfines Durant les dernières décennies, la métathèse des oléfines est devenue un des outils les plus puissants et attractifs pour la formation de doubles liaisons carbone-carbone pour la préparation d'une large gamme de produits allant des alcènes simples aux molécules complexes d'intérêt biologique et aux polymères. L'importance du développement de cette réaction catalytique en synthèse organique a été reconnue par l'attribution du prix Nobel de Chimie en 2005 conjointement à Yves Chauvin, Robert H. Grubbs et Richard R.Schrock.

Figure 1 .

 1 Figure 1. Les catalyseurs de métathèse à base de ruhénium les plus communs: catalyseur de Grubbs de première génération (G-I), catalyseur de Grubbs de deuxième génération (G-II), catalyseur de Hoveyda-Grubbs de seconde génération (HG-II).

  du travail a été la modification de catalyseurs du ruthénium de type Grubbs et Hoveyda à partir des complexes commerciaux G-II et HG-II par remplacement du ligand carbène N-hétérocyclique classique N,N'bis(mésityl)imidazolinylidene par un analogue fluoré.

Figure 4

 4 Figure 4

Schéma 4

 4 Les complexes 15 et 16 ont été caractérisés par spectroscopie RMN du proton, du carbone et du fluor, et par analyse élémentaire. Des structures ont été obtenues par diffraction des rayons X à partir des complexes 16 (Figure5).

Figure 6 2. 4 .

 64 Figure 5

Figure 7

 7 Figure 7

Table 1 .

 1 AROCM of norbornenedicarboxylic anhydride and styrene.

	Catalyst	Time	Conversion Yield
	2a	66 h	>99%	35%
	2b	22 h	>99%	55%
	2c	25 min >99%	85%

In 2006 R. Grubbs et al. described two catalysts that contain fluorine in ortho-positions in NHC ligand (3a and 3b,

Scheme 6)

Table 2 .

 2 Synthesis of bafilomycin-type lactone by RCM and the results of catalysis.However, the best results were obtained with the first-generation catalyst 50, synthesis of that was described in the same paper (Scheme 29)63 .

	Catalyst Mol. % Conversion Z/E Yield
	G-I	20	~10%	1:1	-
	G-I	20+20	>90%	7:3	-
	47a	5	~35%	7:3	-
	48a	5	~35%	7:3	-
	50	5	~35%	7:3	-
	50	10+10	>90%	7:3	48%

or 47b 64 . Scheme 30. Synthesis of complexes 51 and 52.

Scheme 32. Synthesis of catalyst 54@rGO.

	Some fluorinated latent catalysts are known as well. N.G. Lemcoff et al. described catalyst 55,
	that contains benzylidene ligands with chelating trifluoromethylthio-group (Scheme 33) 69 .
	Catalyst was synthesized in two steps from the commercially available (2-
	bromophenyl)(trifluoromethyl)sulfane.
	Scheme 33. Synthesis of complex 55.

Scheme 34. Synthesis of complex 57.

	M. Matsugi et al. described synthesis of catalysts 59, containing directly bonded fluorous tag with
	aromatic core of benzylidene ligand (Scheme 35) 72,73 . Direct perfluoralkylation of salicylaldehyde
	was carried out in presence of cesium carbonate as soft base and radical initiator V-70L (light
	fraction of commercially available initiator V-70 with m.p. 58°С 74 , (±)-2,2'-azobis(2,4-dimethyl-
	4-methoxyvaleronitrile) 75 ) that provided soft conditions of the reaction.

Scheme 35. Synthesis of complexes 59.

	These catalysts have demonstrated higher activity than HG-II or 42 (see Scheme 23) in RCM of
	N,N-diallyltosylamide, DEAMM and DEDAM. Catalyst 59a has demonstrated ability for
	recyclization using F-SPE. During five cycles, this catalyst provided excellent yields both for
	metathesis and for amount of regenerated catalyst, while 59b proved to be not able to regeneration
	by F-SPE.
	M. Mauduit et al. have described the synthesis of fluoro-containing Hoveyda-type catalysts
	containing sulfonamide groups 76 . Corresponding styrenes for synthesis of 60a-c were obtained via
	sulfonation of 4-isopropoxy-3-vinylaniline by triflic anhydride or arenesulfonyl chloride (Scheme
	36). All synthesized catalysts were investigated in RCM of DEAMM and CM of several substrates.
	However, fluoro-

containing catalysts 60a-c have not demonstrated good results. Scheme 36. Synthesis of complexes 60.

	way for further synthetically facile fine-tuning. Introduction of fluorinated group was implemented
	via acylation of corresponding amide (or amine) by pentafluorobenzoyl chloride. Indenylidene
	complexes M2 and M21 were used and ruthenium source.
	M. Mauduit et al. described synthesis of catalysts 61a, 62a-c, 63b (Scheme 37) containing 1,4-
	oxazine moiety in benzylidene ligand 77 . This modification of Hoveyda-type complexes opened the

Scheme 37. Synthesis of complexes 61, 62, and 63.

14, 65a,b, 66 and 68 were

  described. Introduction of perfluoroalkyl group was performed by mean of Ullmann reaction. Catalysts

	mentioned above the synthesis of perfluoroalkyl-containing
	styrenes 12a,b (Scheme 39) and 67 (Scheme 40) and the corresponding light-fluorous catalysts

14, 65a,b and 66 demonstrated high activity in RCM reactions. Scheme 39. Synthesis of styrenes 12a,b and complexes 14, 65a,b, and 66.

Scheme 44. Synthesis of complex 75.

	The resulting catalyst has shown good turnover number in methyl oleate ethenolysis (TON =
	4300), while, for example, analogous methoxy-containing catalyst 76 showed only TON = 1800.
	Such big difference could be explained by high electron-withdrawing properties of
	pentafluorophenyl group, that decreases Ru-O bond strength and accelerates initiation step of
	metathesis reaction 87 .
	Another modification of chelating indenylidene ligand was described by C. Bruneau et al. 88 . The
	fluorinated moiety was introduced into substrate by condensation of 3,5-
	diisopropoxyphenyllithium with 2,6-difluorobenzaldehyde (Scheme 45). Synthesis of carbene
	complex 77 was carried out in the green solvent dimethylcarbonate (DMC). The resulting complex
	78 demonstrated good thermal stability and activity in RCM of DEDAM and DEAMM.
	. Introduction of fluorinated group was carried out by treatment of
	pentafluorophenylmagnesium bromide with 3,5-diisopropoxy-N-methoxy-N-methylbenzamide.

Scheme 45. Synthesis of complex 78.

	Scheme 46. Synthesis of complex 79a.
	Second-generation catalyst 79b (Scheme 47), its activity in selected examples of RCM, RCEYM,
	and ROMP reactions with stability test have been described last year 91 . This catalyst demonstrated
	almost the same behavior with parental complex M2 in every case.
	Scheme 47. Synthesis of complex 79b.
	In 2003 P. Dixneuf, C. Bruneau et al. published the first example of cationic allenylidene Ru-
	complex 80 containing fluorine atom in para-position of phenyl group (Scheme 48) 92 .
	Indenylidene complexes 79a and 79b containing one fluorine atom in para-position has been
	described in publications of F. Verpoort et al. Synthesis and catalytic properties in RCM of
	DEDAM and DEAMM and ROMP of COD of the first-generation catalyst 79a (Scheme 46) have
	been described in 2015 89 . The corresponding propargyl alcohol was synthesized from the
	commercially available p-fluorobenzophenone via the condensation with sodium acetylide 90 .

Scheme 48. Synthesis of complexes 80.

Table 3 .

 3 Partition coefficients (PFMC/toluene) of fluorous phosphines 88 and metathesis catalysts 89.

	Fluorous	Pi(FBS) Fluorous	Pi(FBS)
	Phosphine		Catalyst
	88a	82.3	89a	0.15
	88b	>300	89b	0.66
	88c	>300	89c	3.46
	88d	82.3	89d	0.13

Scheme 56. Synthesis of complexes 89.

Table 1 .

 1 Selected structural data for 16a and 16b

	Complex	HG-II 30	16a	16b
	Bond length
	(Å)
	Ru-C(1) (benzylidene)	1.828(5)	1.832 (4)	1.825(5)
	Ru-C(2)	1.981(5)	1.987(4)	1.975(5)
	(NHC)
	Ru-O	2.261(3)	2.257(3)	2.272(3)
	Ru-Cl 1	2.3279(12) 2.3492(11) 2.3116(14)
	Ru-Cl 2	2.3393(12) 2.3505(11) 2.3393(13)
	Angle (°)
	C(1)-Ru-C(2) 101.59(19) 102.64(17) 101.2(2)
	C(1)-Ru-O	79.28(17) 79.59(15) 78.91(17)
	C(2)-Ru-O 176.22(14) 177.69(14) 177.96(16)
	Cl 1 -Ru-Cl 2	156.47(5) 159.88(5) 156.80(6)
	C(1)-Ru-Cl 1 100.18(15) 98.37 (14) 98.92(15)
	C(1)-Ru-Cl 2 100.12(15) 98.54(14) 100.30(15)
	C(2)-Ru-Cl 1 96.59(12) 93.46(11) 97.02(13)
	C(2)-Ru-Cl 2 90.89(12) 93.40(11) 91.86(14)
	Torsion angle
	(°)
	C(2)-Ru-	171.0(3)	176.2(3)	176.6(4)
	C(1)-C(3)
	Cl 1 -Ru-C(1)-	78.0(3)	80.8(3)	84.1(4)
	C(3)
	Cl 2 -Ru-C(1)-	90.1(3)	88.3(3)	82.9(4)
	C(3)

Table 2 .

 2 Catalytic activity of G-II type complexes in RCM

	Time,			Conversion of DEDAM, %
	min	G-II	15a	15b	27a	27b	41
	5	36	38	32	78	83	27
	10	69	66	59	88	91	50
	30	96	98	98	93	95	78

Table 3 .

 3 Catalytic activity of phosphine-free HG-II type complexes in RCM

	Time,			Conversion of DEDAM, %
	min	HG-II	16a	16b	28a	28b	32b	32c	42
	10	80	3	1	5	3	1	1	0
	30	98	3	6	37	41	3	3	3
	60	99	58	29	65	67	6	4	15
	120	99	98	75	84	84	13	7	59
	240	-	99	95	92	92	22 a	15 b	90

a 68% after 20 h; b 35% after 20 h

Table 4 .

 4 Catalytic activity of ruthenium complexes of G-II type in CM

	Time,			Conversion of allyl benzene, %
	min	G-II	15a	15b	27a	27b	41
	5	62	86	41	79	78	48
	10	78	83	62	80	80	64
	20	79	82	68	80	82	77
	30	79	82	70	80	82	79

Table 5 .

 5 Catalytic activity of phosphine-free complexes of HG-II type in CM

	Time,			Conversion of allyl benzene, %
	min	HG-II	16a	16b	28a	28b	32b	32c	42
	2	40	45	41	72	69	0	0	10
	5	75	63	45	80	78	0	0	28
	10	73	66	66	81	80	0	0	45
	20	72	73	73	82	84	10	4	61
	30	72	76	76	83	83	15	8	65

  Organic layers were concentrated to the dryness under reduced pressure. 6 M HCl (300 mL) was added to the residue, and the mixture was stirred at r.t. for 3 h. The formed precipitate was separated by filtration, washed with petroleum ether, and treated with saturated solution of NaHCO3 (200 mL) under stirring at r.t. for 1 h. The resulting solid was filtered off and dried to the constant weight to yield 17.2 g of 2 as a white solid. Yield: 72%. mp 84-85 °C.

	mixture of 2,6-dimethylaniline (10.0 g, 82.6 mmol), hexafluoroacetone sesquihydrate (30 g, 153.8 mmol), and PTSA (200 mg, 1.1 mmol) was heated at 100 °C for 20 h. After cooling to r.t., water (50 mL) was added and a resulting mixture was extracted with EtOAc (3 × 30 mL). The combined organic layers were washed with H2O and brine and then dried over MgSO4. The solvent was removed under reduced pressure, and the resulting solid was recrystallized from petroleum ether to give 22.7 g of the corresponding hexafluoroisopropoxyl aniline 1. Yield: 95%. 1 H NMR (400 MHz, DMSO-d6): δ 8.17 (s, 1H, OH), 7.10 (s, 2H, HAr), 4.90 (s, 2H, NH2), 2.11 (s, 6H, Me); 13 C{ 1 H} NMR (101 MHz, DMSO-d6): δ 145.9, 126.2, 123.4 (q, 1 JC,F = 288 Hz), 120.2, Aniline 1 (22.7 g, 79.2 mmol) was further treated with benzaldehyde (12.0 g, 113 mmol) in toluene (150 mL) in the presence of PTSA (0.7 g, 4 mmol) under refluxing in a Dean-Stark apparatus for 3 h. After cooling to r.t. and toluene removal, the residue was redissolved in acetonitrile (150 mL). Iodomethane (2.7 g, 98 mmol) and potassium carbonate (20.8 g, 151 mmol) were added to the solution, and the mixture was stirred at 70 °C for 5 h. Then, the cooled (r.t.) reaction mixture was treated with H2O (100 mL) and extracted with EtOAc (3 × 116.8, 76.8 (hept, Synthesis of 4-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-2,6-dimethylaniline (2). 100 mL).

2

JC,F = 29 Hz), 18.2;

19

F{ 1 H} NMR (376 MHz, DMSO-d6): δ -74.20 (s). Elemental analysis calcd (%) for C11H11F6NO: C, 46.00; H, 3.86; N, 4.88; found: C, 45.93; H, 3.95; N, 4.92. 1 H NMR (400 MHz, CDCl3): δ 7.12 (s, 2H, HAr), 3.79 (s, 2H, NH2), 3.47 (s, 3H, OMe), 2.22 (s, 6H, Me); 13 C{ 1 H} NMR (101 MHz, CDCl3): δ 144.6, 128.2, 122.9 (q, 1 JC,F = 288 Hz), 121.5, 115.8, 83.1 (quint, 2 JC,F = 28 Hz), 54.0, 18.0; 19 F{ 1 H} NMR (376 MHz, CDCl3): δ -71.08 (s). Elemental analysis calcd (%) for C12H13F6NO: C, 47.85; H, 4.35; N, 4.65; found: C, 47.79; H, 4.43; N, 4.58.

  Compound 3 (11.1 g, 29.4 mmol) was further dissolved in acetone (190 mL), and then sodium iodide (11.0 g, 73.4 mmol) was added. The reaction mixture was stirred at r.t. for 24 h. After filtration, the mother liquor was concentrated, and the residue was dissolved in EtOAc (50 mL) and washed with a 5% solution of Na2S2O3 (50 mL). The organic layer was separated, and the aqueous layer

	was extracted with EtOAc (3 × 30 mL). Combined organic layers were dried
	using CaCl2, filtered, and concentrated. The crude product was recrystallized
	from petroleum ether to give 9.8 g of iodoacetamide 4 as a white solid. Yield: 71%. 1 H NMR (400
	MHz, Acetone-d6): δ 9.08 (s, 1H, NH), 7.33 (s, 2H, HAr), 3.98 (s, 2H, CH2), 3.51 (s, 3H, OMe),
	2.34 (s, 6H, Me); 13 C{ 1 H} NMR (101 MHz, Acetone-d6): δ 167.1, 137.6, 128.4, 126.4, 123.5 (q,
	1 JC,F = 290 Hz), 83.6 (q, 2 JC,F = 28 Hz), 54.9, 18.7, -0.8; 19 F{ 1 H} NMR (376 MHz, Acetone-d6): δ
	-71.40 (s). Elemental analysis calcd (%) for C14H14F6INO2: C, 35.84; H, 3.01; N, 2.99; found: C,
	35.76; H, 3.13; N, 2.89.
	1 H NMR (400 MHz, CDCl3):
	δ 7.91 (s, 1H, NH), 7.30 (s, 1H, HAr), 4.26 (s, 2H, CH2), 3.49 (s, 3H, OMe), 2.30 (s, 6H, Me);
	19 F{ 1 H} NMR (376 MHz, CDCl3): δ -70.75 (s). Elemental analysis calcd (%) for C14H14ClF6NO2:
	C, 44.52; H, 3.74; N, 3.71; found C, 44.34; H, 3.89; N, 3.63.

Synthesis of N-[4-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-2,6-dimethylphenyl]-2-iodoacetamide (4).

  JH,H = 6.0 Hz, 2H, CH2), 2.36 (s, 6H, o-CH3), 2.21 (s, 6H, o-CH3), 2.17 (s, 3H, p-CH3); 13 C{ 1 H} NMR (101 MHz, Acetone-d6): δ 149.6, 144.47, 131.8, 131.0, 130.1, 129.3, 129.2, 123.8 (q, 1 JC,F = 290 Hz), 119.0, 83.7 (q, 2 JC,F = 28 Hz), 54.5, 49.4, 48.8, 20.7, 19.5, 18.5; 19 F{ 1 H}

	NMR (376 MHz, Acetone-d6): δ -71.55 (s). Elemental analysis calcd (%) for C23H28F6N2O: C,
	59.73; H, 6.10; N, 6.06; found: C, 59.71; H, 6.12; N, 5.99.

  9.3 g of 10 as a beige solid. Yield: 80% (75% for 2 steps). mp 148-150 °C. 1 H NMR (600 MHz, CDCl3): δ 13.78 (s, 1H, NH), 7.34 (s, 1H, HAr), 7.16 (s, 1H, HAr), 6.87 (s, 2H, Mes HAr), 4.01 (s, 1H, NH), 3.26-3.22 (m, 2H, CH2), 3.08-3.03 (m, 2H, CH2), 2.35 (s, 3H, Me), 2.35 (s, 3H, Me), 2.31 (s, 6H, Mes o-CH3), 2.25 (s, 3H, Me); 13 C{ 1 H} NMR (151 MHz, CDCl3): δ 142.3, 141.6, 136.4, 135.6, 133.7, 132.7, 130.6, 129.8, 127.5, 124.2, 123.5 (q, 1 JC,F = 288 Hz), 80.5 (quint, 2 JC,F

	= 29 Hz), 51.0, 47.8, 21.3, 20.7, 18.5, 17.2; 19 F{ 1 H} NMR (282 MHz, CDCl3): δ -75.55 (s).
	Elemental analysis calcd (%) for C22H26F6N2O: C, 58.92; H, 5.84; N, 6.25; found: C, 58.85; H,
	5.93; N, 6.20.
	75 (s, 2H, CH2), 2.35 (s, 3H,
	CH3), 2.28 (s, 6H, CH3), 2.22 (s, 3H, CH3), 2.18 (s, 3H, CH3); 19 F{ 1 H} NMR (282 MHz, CDCl3):
	δ -73.31 (s).
	This compound was further dissolved in anhydrous toluene (150
	mL), and BH3•SMe2 (58.3 mL of 2 M solution in THF, 116.6 mmol)
	was added dropwise under an argon atmosphere at r.t. The resulting
	mixture was stirred at 90 °C for 3 h. After cooling to r.t., MeOH was
	slowly added until ceasing of gas evolution. Then, a 5% solution (300
	mL) of HCl was added and resulting mixture was extracted with EtOAc (2 × 120 mL). The aqueous

1

H NMR (300 MHz, CDCl3): δ 9.47 (br.s, 1H, NHCO), 7.77 (br.s, 1H, OH), 7.34 (s, 1H, HAr), 7.27 (s, 1H, HAr), 6.80 (s, 2H, HAr), 4.07 (br.s, 1H, NH), 3.layer was separated, treated with NaHCO3, and extracted with EtOAc (2 × 120 mL). Combined organic layers were washed with a saturated solution of NaHCO3, dried over MgSO4, and concentrated under reduced pressure. The crude product was recrystallized from petroleum ether to give

  JC,F = 30 Hz), 55.7, 53.0, 51.7, 21.5, 21.1, 18.7, 17.9, 17.4; 19 F{ 1 H} NMR (376 MHz, CDCl3): δ -67.22 (s, 3F), -70.97 (br.s, 3F), -78.87 (s, 3F). Elemental analysis calcd (%)

	1 H NMR (400 MHz, CDCl3): δ 8.43 (s, 1H, NCHN), 7.42 (s, 1H, HAr), 7.31 (s, 1H, HAr), 6.94 (s,
	2H, Mes HAr), 4.54-4.24 (m, 4H, 2CH2), 3.57 (s, 3H, OMe), 2.43 (s, 3H, Me), 2.40 (s, 3H, Me),
	2.34 (s, 3H, Me), 2.28 (s, 3H, Me), 2.26 (s, 3H, Me); 13 C{ 1 H} NMR (101 MHz, CDCl3): δ 161.3,
	141.4, 140.9, 139.0, 135.8, 135.2, 134.7, 130.5, 130.4-130.0 (m), 129.9, 124.2, 123.5, 122.1, 121.3,
	120.6, 119.0, 83.5 (t, 2

for C25H27F9N2O4S: C, 46.00; H, 3.86; N, 4.88; found: C, 45.97; H, 3.88; N, 4.86.

  H NMR (400 MHz, C6D6): δ 19.79, 19.53 (s, 1H, CHPh), 8.35 (s, 1H, HAr), 7.61 (s, 1H, HAr), 7.05-6.71 (m, 6H, HAr), 6.23 (s, 1H), 3.33-1.04 (m, 54H); 13 C{ 1 H} NMR (101 MHz, C6D6): δ 296.7 (d, 2 JC,P = 122 Hz), 295.8 (d, 2 JC,P = 134 Hz) 221.5 (d, 2 JC,P = 76 Hz), 220.3 (d, 2 JC,P = 79 Hz),

	153.2, 152.0, 142.5, 141.2, 140.2, 139.2, 138.9, 138.5, 137.7, 137.5, 137.1, 135.6, 130.4, 129.5,
	128.8, 128.7, 128.6, 128.4, 127.5, 123.4 (q, 1 JC,F = 290 Hz), 123.0 (q, 1 JC,F = 290 Hz), 84.0-82.8
	(m), 54.5, 54.3, 52.1, 51.6, 51.3, 33.0, 32.9, 32.1, 31.9, 29.6, 29.3, 28.3, 28.2, 27.9, 27.8, 26.7,
	26.5, 21.2, 21.0, 20.8, 20.5, 19.4, 19.0; 19 F{ 1 H} NMR (376 MHz, C6D6): δ -70.24 (s); 31 P{ 1 H}
	NMR (162 MHz, C6D6): δ 28.00 (s), 23.07 (s). Elemental analysis calcd (%) for
	C49H65Cl2F6N2OPRu: C, 57.98; H, 6.45; N, 2.76; found: C, 57.93; H, 6.49; N, 2.74.

  JC,F = 290 Hz), 122.34, 122.27, 113.3, 83.5 (quint, 2 JC,F = 28 Hz), 75.2, 54.2, 21.4, 21.1; 19 F{ 1 H} NMR (282 MHz, C6D6): δ -70.09 (s). Elemental analysis calcd (%) for C34H38Cl2F6N2O2Ru: C, 51.52; H, 4.83; N, 3.53; found: C, 51.49; H, 4.86; N, 3.53. CCDC 1030291 contains the supplementary crystallographic data for this compound.

	1 H NMR (600 MHz, C6D6): δ
	16.61 (s, 1H, CHAr), 7.64 (s, 2H, HAr), 7.11 (d, JH,H = 7.4 Hz,
	1H, HAr), 7.08 (m, 1H, HAr), 6.87 (s, 2H, ArH), 6.64 (t, JH,H = 7.4
	Hz, 1H, HAr), 6.30 (d, JH,H = 8.3 Hz, 1H, HAr), 4.46 (hept, 3 JH,H
	= 6.0 Hz, 1H, CHMe2), 3.35 (m, 2H, 2CH2), 3.28 (m, 5H, 2CH2,
	OMe), 2.60 (s, 6H, Me), 2.43 (s, 6H, Me), 2.22 (s, 3H, p-CH3), 1.28 (d, 3 JH,H = 6.1 Hz, 6H,
	CH(sH3)2); 13 C{ 1 H} NMR (151 MHz, C6D6): δ 291.4, 213.2, 152.7, 145.7, 141.4, 138.8, 129.8,
	129.3, 128.7, 128.4, 123.4 (q, 1

  Then a solution of NaBH4 (1.04 g, 27.6 mmol) in 26 mL of water was added dropwise. After full addition, the reaction mixture was stirred another 30 min and extracted with Et2O (3 × 15 mL). Combined organic layer was washed with 10 mL of water, filtered through cotton wool and evaporated under reduced pressure to yield yellow crystals.

	21.2; 19 F{ 1 H} NMR (376 MHz, CDCl3) δ -74.88 (s). Elemental analysis calcd (%) for
	C10H7F6N3O: C, 40.15; H, 2.36; N, 14.05; found: C, 39.91; H, 2.39; N, 14.19.
	2-(2-Azido-5-methoxyphenyl)-1,1,1,3,3,3-hexafluoropropan-2-ol (18b).
	JH,H =8.3 Hz, 1H, HAr), 7.04 (br.s, 1H, OH), 2.38 (s, 3H, Me); 13 C{ 1 H} NMR (101 MHz, CDCl3) δ 135.9, 135.4, 132.3, 130.3 (m), 122.7 (q, 1 JC,F = 289 Hz), 119.8, 119.7, 79.9 (p, 2 JC,F= 30 Hz), Yield: 88%. mp 67-68 °C; 1 H NMR (400 MHz, CDCl3) δ 7.19 (d, J = 8.8 Hz, 1H, HAr), 7.19 (s, 1H, HAr), 7.07 (dd, J = 8.9, 2.7 Hz, 1H, HAr), 7.07 (br.s, 1H, OH), 3.82 (s, 3H, OMe); 13 C{ 1 H} NMR (101 MHz, CDCl3) δ 157.1, 130.3, 122.7 (d, 1 JC,F= 289 Hz), 121.0, 120.8, 116.9, 115.8 (p, 3 JC,F= 3 Hz), 79.8 (p, 2 JC,F= 30 Hz), 55.8; 19 F{ 1 H} NMR (376 MHz, CDCl3) δ -74.94 (s). Elemental analysis calcd (%) for C10H7F6N3O2: C, 38.11; H, 2.24; N, 13.33; found: C, 37.79; H, 2.32; N, 13.45. General procedure for synthesis of 19. A mixture of azide 18 (17.6 mmol), iodomethane (2.2 mL, 35.3 mmol) and anhydrous K2CO3 (4.88 g, 35.3 mmol) in 80 mL of acetonitrile was stirred at r.t. for 2 days. After reaction completion, the solvent was evaporated under reduced pressure, residual solid was dispersed in EtOAc and filtered. The resulting filtrate was evaporated again and purified by flash chromatography using EtOAc/petroleum ether (1:8) as eluent to yield yellow oil that was crystallized after complete removal of solvent under high vacuum. 1-Azido-2-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-4-methylbenzene (19a). Yield: 96%. mp 51-52 °C; 1 H NMR (400 MHz, CDCl3) δ 7.36 (s, 1H, HAr), 7.33 (d, 3 JH,H =8.3 Hz, 1H, HAr), 7.21 (d, 3 JH,H= 8.2 Hz, 1H, HAr), 3.46 (s, 3H, OMe), 2.38 (s, 3H, Me); 13 C{ 1 H} NMR (101 MHz, CDCl3) δ 137.2, 135.0, 132.6, 131.8, 122.6 (q, 1 JC,F = 292 Hz), 120.7, 118.2, 84.3 (p, 2 JC,F = 29 Hz), 54.6, 21.1; 19 F{ 1 H} NMR (376 MHz, CDCl3) δ -69.86 (s). Elemental analysis calcd (%) for C11H9F6N3O: C, 42.18; H, 2.90; N, 13.42; found: C, 42.35; H, 3.11; N, 13.72. 1-Azido-2-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-4-methoxybenzene (19b). Yield: 91%. mp 52-53 °C; 1 H NMR (400 MHz, CDCl3) δ 7.25 (d, 3 JH,H= 8.8 Hz, 1H, HAr), 7.13 (s, 1H, HAr), 7.07 (dd, J = 8.8, 2.8 Hz, 1H, HAr), 3.83 (s, 3H, OMe), 3.48 (s, 3H, OMe); 13 C{ 1 H} NMR (101 MHz, CDCl3) δ 156.8, 132.2, 122.5 (q, 1 JC,F = 291 Hz), 122.0, 119.6, 117.5-117.3 (m), 117.1, 84.9-83.4 (m), 55.8, 54.7; 19 F{ 1 H} NMR (376 MHz, CDCl3) δ -69.87 (s). Elemental analysis calcd (%) for C11H9F6N3O2: C, 40.13; H, 2.76; N, 12.76; found: C, 40.41; H, 2.83; N, 12.97. General procedure for synthesis of 20. The azide 19 (13.8 mmol) was dissolved in 4.3 mL of methanol, then CoCl2•6H2O (290 mg, 1.4 mmol) and cetyltrimethylammonium bromide (CTABr) (426 mg, 1.4 mmol) were added with Yield: 98%. mp 61-63 °C; 1 H NMR (400 MHz, CDCl3) δ 7.09 (s, 1H, HAr), 7.06 (d, 3 JH,H= 8.3 Hz, 1H, HAr), 6.65 (d, 3 JH,H= 8.2 Hz, 1H, HAr), 4.56 (br.s, 2H, NH2), 3.56 (s, 3H, OMe), 2.26 (s, 3H, Me); 13 C{ 1 H} NMR (101 MHz, CDCl3) δ 144.1, 132.1, 130.1 (p, 3 JC,F = 2.1 Hz), 127.5, 123.0(q, 1 JC,F =292 Hz), 118.9, 109.4, 85.3 (p, 2 JC,F =28 Hz), 54.8, 20.7; 19 F{ 1 H} NMR (376 MHz, CDCl3) δ-69.84 (s). Elemental analysis calcd (%) for C11H11F6NO: C, 46.00; H, 3.86; N, 4.88; found: C, 45.92; H, 3.97; N, 5.03. 2-(1,1,1,3,3,3-Hexafluoro-2-methoxypropan-2-yl)-4-methoxyaniline (20b). Yield: 92%. mp 51-53 °C; 1 H NMR (400 MHz, CDCl3) δ 6.88 (s, 1H, HAr), 6.88 (d, 3 JH,H= 9.4 Hz, 1H, HAr), 6.69 (d, 3 JH,H= 9.4 Hz, 1H, HAr), 4.42 (br.s, 2H, NH2), 3.75 (s, 3H, OMe), 3.57 (s, 3H, OMe); 13 C{ 1 H} NMR (101 MHz, CDCl3) δ 152.1, 140.4, 123.0 (q, 1 JC,F = 292 Hz), 120.0, 118.0, 115.3-115.1 (m), 110.3, 85.9-84.3 (m), 55.9, 54.9; 19 F{ 1 H} NMR (376 MHz, CDCl3) δ -69.87 (s). Elemental analysis calcd (%) for C11H11F6NO2: C, 43.57; H, 3.66; N, 4.62; found: C, stirring at r.t. 2-(1,1,1,3,3,3-Hexafluoro-2-methoxypropan-2-yl)-4-methylaniline (20a). 43.89; H, 4.01; N, 4.64.

  JC,F = 290 Hz), 114.8, 85.1 (p,2 JC,F=29 Hz), 54.7, added until ceasing of gas evolution. Then, a 10% solution (60 mL) of HCl was added and resulting mixture was extracted with EtOAc (2 × 20 mL). The aqueous layer was separated, treated with NaHCO3, and extracted with EtOAc (2 × 20 mL). Combined organic layers were washed with a saturated solution of NaHCO3, dried over MgSO4, and concentrated under reduced pressure. The crude product was recrystallized from petroleum ether to yield a beige solid.

	2-Chloro-N-[2-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-4-methylphenyl]acetamide (21a). Yield: 87%. mp 70-71 °C; 1 H NMR (400 MHz, CDCl3) δ 9.78 (s, 1H, NH), 8.43 (d, JH,H = 8.5 Hz, 1H, HAr), 7.32 (d, JH,H= 8.6 Hz, 1H, HAr), 7.29 (s, 1H, HAr), 4.19 (s, 2H, CH2), 3.54 (s, 3H, OMe), 2.37 (s, 3H, Me); 13 C{ 1 H} NMR (101 MHz, CDCl3) δ 164.0, 134.9, 134.8, 132.2, 130.2 (m), diamine (24a). Yield: 90%; mp 53-54 °C; 1 H NMR (400 MHz, CDCl3) δ 7.13 (d, 3 JH,H =8.9 Hz, 1H, HAr), 7.11 (s, 1H, HAr), 6.86 (s, 2H, HAr), 6.72 (d, 3 JH,H = 8.4 Hz, 1H, HAr), 5.70 (br.s, 1H, NH), 3.54 (s, 3H, OMe), 3.46-3.39 (m, 2H, CH2), 3.20 (t, 3 JH,H =5.9 Hz, 2H, CH2), 2.30 (s, 6H, Me), 2.27 (s, 3H, Me), 2.25 (s, 3H, Me); 13 C{ 1 H} NMR (101 MHz, CDCl3) δ 146.2, 132.2, 130.8, 130.7, 129.7, 125.6, 123.0 (q, 1 JC,F = 293 Hz), 112.8, 108.7, 85.7 (p, 1 JC,F = 28 Hz), 54.6, 48.1, 44.7, 20.7, 20.6, 18.2; 19 F{ 1 H} NMR (376 MHz, CDCl3) δ -69.46 (s). Elemental analysis calcd 123.21 (s), 122.5 (q, 1 N 1 -[2-(1,1,1,3,3,3-Hexafluoro-2-methoxypropan-2-yl)-4-methylphenyl]-N 2 -mesitylethane-1,2-(%) for C22H26F6N2O: C, 58.92; H, 5.84; N, 6.25; found: C, 58.81; H, 5.87; N, 5.96.

  HAr), 6.98 (dd, JH,H = 1.5, 7.4 Hz, 1H, HAr), 6.92 (br.s, 1H, HAr), 6.89 (s, 1H, HAr), 6.83 (s, 1H, HAr), 6.58 (t,3 JH,H = 7.4 Hz, 1H, HAr), 6.42 (d,3 JH,H = 8.3 Hz, 1H, HAr), 4.56 (hept,3 JH,H = 6.1 Hz, 1H,

	Yield: 71%. 1 H NMR (500 MHz, Toluene-d8, 80 °C) δ 16.92 (br.s, The reaction was finished in 1 day. Yield: 96%. mp 74-76 °C.
	1H, CHAr), 9.13 (br.s, 1H, HAr), 7.61 (s, 1H, HAr), 7.10 (m, 1H, 1 H NMR (400 MHz, CDCl3) δ 9.13 (s, 1H, NHCO), 7.26 (s, 2H,
	HAr), 3.47 (s, 5H, CH2, OMe), 2.92 (hept, 3 J = 6.1 Hz, 1H,
	CHMe2), 2.27 (s, 6H, Me), 2.21 (br.s, 1H, NHCH2), 1.14 (d, 3 J
	= 6.2 Hz, 6H, CH(CH3)2); 13 C{ 1 H} NMR (101 MHz, CDCl3) δ 170.5, 136.5, 135.7, 128.0, 126.2,
	CHMe2), 4.48 (td, JH,H =9.6, 3.2 Hz, 1H, CH2), 3.85 (s, 3H, OMe), 122.5 (q, 1 JC,F = 289 Hz), 83.7-82.1 (m), 54.4, 50.3, 50.0, 23.0, 19.1; 19 F{ 1 H} NMR (376 MHz,
	-[2-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-4-methylphenyl]-3-mesityl-4,5-3.70 (m, 1H, CH2), 3.48 (m, 1H, CH2), 3.40 (m, 1H, CH2), 3.38 (s, 3H, OMe), 2.52 (s, 3H, Me), CDCl3) δ -70.80 (s). Elemental analysis calcd (%) for C17H22F6N2O2: C, 50.87; H, 5.59; N, 6.94;
	dihydroimidazol-2-ylidene}(2-isopropoxybenzylidene)ruthenium(II) (28a). 2.39 (s, 3H, Me), 2.22 (s, 3H, Me), 1.32 (d, 3 JH,H = 6.1 Hz, 6H, CH(CH3)2); 13 C{ 1 H} NMR (126 found: C, 51.00; H, 5.54; N, 7.00.
	Yield: 74%. 1 H NMR (500 MHz, Toluene-d8, 80 °C) δ 16.91 (s, 1H, MHz, Toluene-d8, 80 °C) δ 294.0, 216.8, 159.7, 153.3, 145.7, 138.8, 138.7, 137.8, 134.7 (br.s), 2-(Cyclohexylamino)-N-[4-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-2,6-dimethylphenyl]-
	CHAr), 9.14 (br.s, 1H, HAr), 7.78 (s, 1H, HAr), 7.21 (br.s, 1H, HAr), 130.4, 130.1, 129.5, 129.1, 123.8 (q, 1 JC,F = 293 Hz), 123.4 (q, 1 JC,F = 289 Hz), 122.4, 122.3, 113.4, acetamide (29c).
	7.10 (m, 1H, HAr), 6.94 (dd, JH,H = 7.5, 1.1 Hz, 1H, HAr), 6.89 (s, 1H, 85.3 (hept, 1 JC,F = 27 Hz), 75.1, 58.0, 55.4, 54.8 (br.s), 53.0 (br.s), 22.3, 22.2, 22.1, 21.9; 19 F{ 1 H} The reaction was finished in 1 day. Yield: 98%. mp 96-98
	HAr), 6.82 (s, 1H, HAr), 6.59 (t, 3 JH,H= 7.4 Hz, 1H, HAr), 6.43 (d, 3 JH,H NMR (282 MHz, Toluene-d8, 60 °C) δ -65.89, -70.73. Elemental analysis calcd (%) for °C. 1 H NMR (400 MHz, CDCl3) δ 9.11 (br.s, 2H, NHCO),
	=8.3 Hz, 1H, HAr), 4.56 (hept, 3 JH,H= 6.3 Hz, 1H, CHMe2), 4.51 (m, C33H36Cl2F6N2O3Ru: C, 49.88; H, 4.57; N, 3.53; found: C, 49.91; H, 4.52; N, 3.27. CCDC 1543695 7.26 (s, 2H, HAr), 3.47 (s, 5H, CH2, OMe), 2.52-2.47 (m,
	1H, CH2), 3.86 (s, 3H, OMe), 3.69 (q, JH,H= 9.9 Hz, 1H, CH2), 3.48 (q, JH,H =9.9 Hz, 1H, CH2), contains the supplementary crystallographic data for this compound. 1H, HCy), 2.27 (s, 6H, Me), 1.96-1.06 (m, 10H, HCy);
	3.42 (q, JH,H= 9.3 Hz, 1H, CH2), 2.51 (s, 3H, Me), 2.37 (s, 3H, Me), 2.21 (s, 3H, Me), 2.16 (s, 3H, 13 C{ 1 H} NMR (101 MHz, CDCl3) δ 170.8, 136.2, 135.7, 128.0, 126.1, 122.5 (q,
	Me), 1.39 (s, 3H, CH(CH3)2), 1.31 (d, (hept, 1 JC,F =27 Hz), 75.1, 58.0, 54.6 (br.s), 53.1 (br.s), 22.4, 22.2, 22.1, 21.9; 19 F{ 1 H} NMR (471 solution of NaHCO3 (20 mL) and extracted with ethylacetate (3 × 20 mL). Combined organic
	MHz, Toluene-d8, 60 °C) δ -65.6 (br.s, 3F), -71.7 (br.s, 3F). Elemental analysis calcd (%) for layers were washed with brine and water, dried over MgSO4, filtered and concentrated under
	C33H36Cl2F6N2O2Ru: C, 50.90; H, 4.66; N, 3.60; found: C, 50.78; H, 4.89; N, 3.42. CCDC 1543696 reduced pressure. The excess of starting amine was removed under high vacuum. The resulting
	contains the supplementary crystallographic data for this compound. solid residue was recrystallized from petroleum ether.
	2-(tert-Butylamino)-N-[4-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-2,6-dimethylphenyl]-
	acetamide (29a).
	The reaction was finished in 3 days. Yield: 95%. mp 126-128
	°C. 1 H NMR (400 MHz, CDCl3) δ 9.19 (s, 1H, NHСО), 7.27
	(s, 2H, HAr), 3.48 (s, 3H, OMe), 3.43 (s, 2H, CH2), 2.28 (s, 6H,
	Me), 1.70 (br.s, 1H, NHCH2), 1.17 (s, 9H, C(CH3)3); 13 C{ 1 H}
	Dichloro{1-[2-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-4-methoxyphenyl]-3-mesityl-4,5-NMR (101 MHz, CDCl3) δ 171.2, 136.3, 135.7, 128.1, 126.1, 122.5 (q, CF3, 1 JC,F = 290 Hz), 83.7-
	dihydroimidazol-2-ylidene}(2-isopropoxybenzylidene)ruthenium(II) (28b). 82.1 (m, C(CF3)2), 54.4, 51.4, 46.3, 29.2, 19.2; 19 F{ 1 H} NMR (376 MHz, CDCl3) δ -70.79 (s).
	Elemental analysis calcd (%) for C18H24F6N2O2: C, 51.94; H, 5.89; N, 6.72; found: C, 52.17; H,
	5.84; N, 6.76.

3

JH,H =6.1 Hz, 3H, CH(CH3)2);

[START_REF] Lam | Synthesis and Evaluation of Molybdenum and Tungsten Monoaryloxide Halide Alkylidene Complexes for Z-Selective Cross-Metathesis of Cyclooctene and Z-1,2-Dichloroethylene[END_REF]

C{ 1 H} NMR (126 MHz, Toluene-d8, 80 °C) δ 294.0, 216.8, 153.3, 145.6, 142.4, 138.8, 138.7, 137.8, 134.1 (br.s), 130.4, 130.1, 130.0, 129.5, 123.8 (q, 2 JC,F = 289 Hz), 123.4 (q, 2 JC,F = 289 Hz), 122.4, 122.3, 113.4, 85.4 General procedure for synthesis of aminoacetamides 29. Chloroacetamide 3 (1.5 g, 4.0 mmol) was dissolved in 20-fold excess of a corresponding alkylamine (80 mmol). The reaction mixture was allowed to stir at room temperature until full disappearance of starting material 3 (TLC control). Afterwards the mixture was treated with 10% N-[4-(1,1,1,3,3,3-Hexafluoro-2-methoxypropan-2-yl)-2,6-dimethylphenyl]-2-(isopropylamino)acetamide (29b). 1 JC,F = 290 Hz), 83.7-82.1 (m), 57.8, 54.4, 50.1, 34.0, 26.0, 25.1, 19.1; 19 F{ 1 H} NMR (376 MHz, CDCl3) δ -70.79 (s). Elemental analysis calcd (%) for C20H26F6N2O2: C, 54.51; H, 5.85; N, 6.32; found: C, 54.54; H, 5.95; N, 6.36.

  ).reduced pressure, and the resulting substance was purified by column chromatography using EtOAc/petroleum ether (1:3) as eluent to yield Hoveyda-type catalyst as a green solid.

	{1-tert-Butyl-3-[4-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-2,6-dimethylphenyl]-4,5-
	dihydro-1H-imidazol-2-ylidene}dichloro(2-isopropoxybenzylidene)ruthenium(II) (32a).
	Yield: 70%. 1 H NMR (400 MHz, C6D6) δ 17.10 (s, 1H, CHAr),
	7.54 (s, 2H, HAr), 7.18 (t, JH,H = 8.0 Hz, 1H, HAr), 7.13 (d, JH,H
	= 7.7 Hz, 1H, HAr), 6.73 (t, JH,H = 7.3 Hz, 1H, HAr), 6.45 (d, JH,H
	= 8.1 Hz, 1H, HAr), 4.58 (hept, 3 JH,H = 5.9 Hz, 1H, CHMe2),
	3.21 (s, 3H, OMe), 3.15-3.01 (m, 4H, CH2), 2.29 (s, 6H, Me),
	2.08 (s, 9H, C(CH3)3), 1.53 (d, 3 JH,H = 6.0 Hz, 6H, CH(CH3)2);
	13 C{ 1 H} NMR (101 MHz, C6D6) δ 306.0, 209.1, 153.0, 146.2, 144.5, 140.1, 130.5, 128.9, 123.4
	(q, 1 JC,F = 291), 123.4, 122.6, 113.7, 84.0-82.9 (m), 74.6, 56.3, 54.2, 51.1, 45.8, 29.7, 22.4, 18.9;
	19 F{ 1 H} NMR (376 MHz, C6D6) δ -70.20 (s). Elemental analysis calcd (%) for
	C29H36Cl2F6N2O2Ru: C, 47.68; H, 4.97; N, 3.83; found: C, 47.87; H, 5.11; N, 3.86.
	Dichloro{3-(4-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-2,6-dimethylphenyl)-1-isopropyl-
	4,5-dihydro-1H-imidazol-2-ylidene}(2-isopropoxybenzylidene)ruthenium(II) (32b).
	5.8 Hz, 1H, NCHMe2), 4.72 (hept, 3 JH,H = 5.8 Hz, 1H,
	OCHMe2), 3.29 (s, 3H, OMe), 3.16-3.04 (m, 4H, CH2), 2.25 (s,
	6H, Me), 1.78 (d,
	Yield: 99%. mp 58-60 °C. 1 H NMR (400 MHz, CDCl3) δ 7.11
	(s, 2H, HAr), 4.09 (br.s, 2H, NH), 3.45 (s, 3H, OMe), 3.17 (t,
	JH,H = 5.6 Hz, 2H, CH2), 2.79 (t, JH,H = 5.6 Hz, 2H, CH2), 2.32

(s, 6H, Me), 1.12 (s, 9H, C(CH3)3);

[START_REF] Lam | Synthesis and Evaluation of Molybdenum and Tungsten Monoaryloxide Halide Alkylidene Complexes for Z-Selective Cross-Metathesis of Cyclooctene and Z-1,2-Dichloroethylene[END_REF]

C{ 1 H} NMR (101 MHz, CDCl3) δ 148.6, 128.7, 127.8, 122.8 (q, 1 JC,F = 291 Hz), 118.7, 83.9-82.2 (m), 54.1, 50.4, 48.7, Yield: 39%. 1 H NMR (400 MHz, C6D6) δ 16.46 (s, 1H, CHAr), 7.59 (s, 2H, HAr), 7.23-7.15 (m, 2H, HAr), 6.79 (t, JH,H = 7.4 Hz, 1H, HAr), 6.49 (d, JH,H = 8.2 Hz, 1H, HAr), 5.84 (hept,

3

JH,H =

  JC,F = 292 Hz), 121.6, 84.5 (hept,2 JC,F = 29 Hz), 54.7, 21.2, 18.5;19 F{ 1 H} NMR (376 MHz, CDCl3) δ -70.04 (s). Elemental analysis calcd (%) for C12H11F6N3O: C, 44.05; H, 3.39; N, 12.84; found: C, 43.86; H, 3.41; N, 12.64.The reaction mixture was allowed to stir at room temperature until full disappearance of starting A mixture of diamine 36 (1.3 g, 4.8 mmol), hexafluoroacetone sesquihydrate (3.7 g, 19.2 mmol), and PTSA (5 mg, 0.03 mmol) was heated at 100 °C for 20 h. After cooling to r.t., water (50 mL) was added and the resulting mixture was extracted with EtOAc (3 × 30 mL). The combined organic layers were washed with water and brine and then dried over MgSO4. The solvent was removed under reduced °C. The reaction mixture was stirred at r.t. for 1 h, and then 5% aqueous solution of hydrochloric acid (20 mL) was added to the mixture. The organic layer was separated; the aqueous layer was extracted with diethyl ether (2 × 20 mL). Combined organic layers were washed with water, dried over MgSO4, filtered, and concentrated under reduced pressure. The crude product was recrystallized from petroleum ether to yield 2.76 g of the corresponding bis-amide as a white solid. Yield: 85%.1 H NMR (300 MHz, Acetone-d6): δ 7.63 (d, J = 6.3 Hz, 4H, HAr), 4.14 (s, 4H, CH2), 2.41 (s, 12H, Me); 19 F{ 1 H} NMR (282 MHz, Acetone-d6): δ -70.81 (s), -74.77 (s). Elemental analysis calcd (%) for C28H22F18N2O4: C 42.44, H 2.80, N 3.54; found: C 42.54, H 3.13, N 3.65.

	122.6 (q, 1 The methylated azide (9.99 g, 30.5 mmol) was dissolved in 10 mL of
	methanol,	then	CoCl2•6H2O	(730	mg,	3.1	mmol)	and
	cetyltrimethylammonium bromide (CTABr) (1.11 g, 3.1 mmol) were added pressure, and the resulting solid was recrystallized from light petroleum and dried
	with stirring at r.t. Then a solution of NaBH4 (2.30 g, 61.1 mmol) in 60 mL of to give 2.5 g of 37 as white powder. Yield: 84%. 1 H NMR (300 MHz, CDCl3): δ
	water was added dropwise. After full addition, the reaction mixture was stirred another 30 min and 7.29 (s, 4H, HAr), 3.49 (s, 2H, NH), 3.27 (s, 4H, CH2), 2.29 (s, 12H, Me); 19 F{ 1 H}
	extracted with Et2O (3 × 30 mL). Combined organic layer was washed with 10 mL of water, NMR (282 MHz, CDCl3): δ -75.58 (s). Elemental analysis calcd (%) for
	filtered through cotton wool and evaporated under reduced pressure to yield 8.95 g of yellow C24H24F12N2O2: C 48.01, H 4.03, N 4.67; found: C 47.99, H 4.16, N 4.93.
	crystals. Yield: 97%. 1 H NMR (400 MHz, CDCl3) δ 7.01 (s, 2H, HAr), 4.60 (br.s, 2H, NH), 3.56 Synthesis of N,N'-(ethane-1,2-diyl)bis(2,2,2-trifluoro-N-(4-(1,1,1,3,3,3-hexafluoro-2-hydroxy-
	(s, 3H, OMe), 2.25 (s, 3H, Me) , 2.18 (s, 3H, Me); 13 C{ 1 H} NMR (101 MHz, CDCl3) δ 142.6, propan-2-yl)-2,6-dimethylphenyl)acetamide) (38).
	133.4, 128.1, 126.5, 124.7, 123.1 (q, 1 JC,F = 293 Hz), 108.7, 85.5 (hept, 2 JC,F = 29 Hz), 54.8, 20.7, TFAA (0.86 g, 8.2 mmol) and pyridine (0.32 g, 8.2 mmol) were added
	18.3; 19 F{ 1 H} NMR (376 MHz, CDCl3) δ -69.61 (s). Elemental analysis calcd (%) for sequentially to the solution of diamine 37 (2.45 g, 4.1 mmol) in diethyl
	JH,H = 6.3 Hz, 6H, OCH(sH3)2); 13 C{ 1 H} NMR (101 MHz, C6D6) δ 285.8, 208.1, 152.9, 144.8, 143.1, 140.3, 129.2, 128.8, 128.5, 123.3 (q, 1 JC,F = 290 Hz), 122.6, 122.2, 113.3, 83.5 (hept, 2 JC,F = 29 Hz), 75.1, 54.2, 52.9, 50.8, 41.8, 22.0, 20.7, 18.7; 19 F{ 1 H} NMR (376 MHz, C6D6) δ -70.22 (s). Elemental analysis calcd (%) for C28H34Cl2F6N2O2Ru: C, 46.93; H, 4.78; N, 3.91; found: C, 46.87; H, 4.89; N, 3.99. C12H13F6NO: C, 47.85; H, 4.35; N, 4.65; found: C, 48.01; H, 4.39; N, 4.63. Chloroacetyl chloride (3.75 g, 33.2 mmol) was added dropwise to the solution of methylated aniline (5 g, 16.6 mmol) and DMAP (2.4 g, 19.9 mmol) in 70 mL of anhydrous CH2Cl2 at 0 °C. The reaction mixture was stirred overnight at r.t. Then, the mixture was concentrated to 30 mL under reduced pressure, treated with 5% HCl (100 mL), and extracted with CH2Cl2 (3 × 50 mL). Combined organic layers were washed with water (30 mL) and dried over MgSO4. After solvent removal under vacuum, the crude acetylated intermediate was purified by flash chromatography using EtOAc/petroleum ether 1:3 as the eluent to yield 3.15 g of the corresponding chloroacetamide 33 as a white solid. Yield: 50%. 1 H NMR (400 MHz, CDCl3) δ 8.55 (s, 1H, NH), 7.25 (s, 1H, HAr), 7.23 (s, 1H, HAr), 4.20 (s, 2H, CH2), 3.46 (s, 3H, OMe), 2.36 (s, 3H, Me), 2.24 (s, 3H, Me); 13 C{ 1 H} NMR (101 MHz, CDCl3) δ 163.8, 138.3, 137.4, 134.6, 131.2, 128.6, 122.7 (q, 1 JC,F = 290 Hz), 122.8, 84.9 (hept, 2 JC,F = 28 Hz), 54.9, 42.8, 21.3, 19.4; ether (40 mL) at 0 Synthesis of N 1 ,N 2 -bis[4-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-2,6-dimethyl-
	19 F{ 1 H} NMR (376 MHz, CDCl3) δ -69.57 (br.s). Elemental analysis calcd (%) for phenyl]ethane-1,2-diamine
	C14H14ClF6NO2: C, 44.52; H, 3.74; N, 3.71; found: C, 44.63; H, 3.91; N, 3.49.
	Dichloro{1-cyclohexyl-3-[4-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-2,6-dimethyl-

phenyl]-4,5-dihydro-1H-imidazol-2-ylidene}(2-isopropoxybenzylidene)ruthenium(II) (32с).

Synthesis of 2-chloro-N-[2-(1,1,1,3,3,3-hexafluoro-2-methoxypropan-2-yl)-4,6-dimethylphenyl]acetamide (33).

General procedure for synthesis of aminoacetamides 34.

Compound 33 (1 g, 2.6 mmol) was dissolved in 20-fold excess of corresponding amine (52 mmol).

Acknowledgements

First of all I would like to sincerely thank my supervisors Prof. Christian Bruneau and Prof. Sergey N. Osipov for offering me the opportunity to work in their groups. I deeply appreciate all the support and encouragement I have received from them during the whole of this thesis. I am grateful to Prof. Pierre H. Dixneuf for his contributions of time and advices. I have learnt a lot from him about organometallic chemistry and France. I am very grateful to Prof. Sergey Z. Vatsadze, Prof. Rinaldo Poli, Prof. Elena Shubina, Prof. Natalia Belkova, who have accepted to evaluate my work.

Scheme 8

The synthesis of new ruthenium complexes was accomplished by traditional ligand exchange method using the reaction of in situ generated carbene with commercially available complexes G-I and HG-I. The reaction were performed in toluene under inert atmosphere, controlled by TLC method leading to the formation of the corresponding products 27 and 28 as air-stable solids of typical dark-brown (27a,b) and dark-green (28a,b) colors in moderate and good yields after column chromatography on silica gel (Scheme 9). atmosphere. The resulting mixture was heated at 80 °С for 8 hours. After cooling to r.t., MeOH was slowly added until ceasing of gas evolution. Then, a 10% solution (20 mL) of HCl was added and resulting mixture was extracted with EtOAc (2 × 30 mL). The aqueous layer was separated, treated with NaHCO3, and also extracted with EtOAc (2 × 20 mL). Combined organic layers were washed with a saturated solution of NaHCO3, dried over MgSO4, and concentrated under reduced pressure.

2-{2-[2-(tert-Butylamino

)ethylamino]-3,5-dimethylphenyl}-1,1,1,3,3,3-hexafluoropropan-2-ol (35a).

Yield: 53%. 1 (41).

2-{2-[2-(Cyclohexylamino

Synthesis of benzylidene(dichloro){1,3-bis

In a flame-dried Schlenk flask compound 40 (300 mg, 0.44 mmol) was mixed with 20 mL of anhydrous toluene. The mixture was cooled to 0 °C, degassed three times, and then KHMDS (460 μL of 1 M solution in THF, 0.46 mmol) was added to the mixture under an argon atmosphere. The reaction mixture was stirred for 30 min; then G-I (305 mg, 0.37 mmol) was added and the mixture was stirred for 2 h at room temperature. After removal of volatiles, the residue was purified by column chromatography on silica gel in a gradient manner using EtOAc/petroleum ether (1:8-1:3) as eluent under an argon atmosphere to yield 130 mg of complex 41 as a brown solid. Yield: 30%.

Catalysis

RCM of diethyl diallylmalonate or diethyl allylmethallylmalonate.

A flame-dried Schlenk flask was charged with solution of catalyst (4.0 µmol, 1.0 mol.%) and dodecane (10 µL) in anhydrous degassed CH2Cl2 (4 mL) under argon atmosphere. The reaction mixture was stirred at 30 °C before starting material (0.4 mmol, 0.1 M) was added via syringe.

Data points were collected over an appropriate period of time by taking the probes (~0.4 mL) from the reaction mixture. The reaction was quenched using excess of ethyl vinyl ether (0.5 mL). The conversion to RCM product was determined by GC.

CM of allylbenzene with cis-1,4-diacetoxy-2-butene.

A flame-dried Schlenk flask was charged with allylbenzene (94.6 mg, 0.8 mmol, 0. The catalytic activity of the new complexes has been investigated on model reactions of intra-and intermolecular olefin metathesis. It was found that most of the synthesized complexes exhibited high activity in cyclization of diethyl diallylmalonate and in cross metathesis of allyl benzene with 1,3-diacetoxybut-2-ene. Their performance has proved to be comparable with commonly used second generation Grubbs and Hoveyda catalysts, with sometimes some differences in the initiation step.

Structural and electronic impact of fluorinated unsymmetrical NHC on reactivity of new ruthenium complexes has been studied. In particular, it was revealed that Hoveyda type catalysts with monoortho-aryl substituted NHC ligands have demonstrated very high initiation rate in CM reactions.

On the contrary, catalysts with more donating N-alkyl NHCs have displayed low activity; for instance, the N-tert-butyl substituted complex has proved to be absolutely inert both in RCM and CM reactions.

Symmetrical ruthenium carbene complexes bearing NHC ligands with two hexafluoroisopropylmethoxy group in para-positions of N-aryl moieties are significantly inferior in reactivity with respect to their asymmetric counterparts showing the strong influence of the desymmetrization factor on catalytic activity. Des modifications des propriétés électroniques et stériques de tous ces ligands peuvent être apportées pour construire des catalyseurs de métathèse plus performants. En particulier l'introduction de ligands fluorés a déjà été tentée avec cet objectif. Ce chapitre rassemble les données relatives à ces travaux présentées dans un ordre chronologique. Pour chaque section, les synthèses de ligands, de complexes du ruthénium et la description des performances en catalyse de métathèse d'oléfines dans des réactions modèles sont décrites. Les complexes carbéniques du ruthénium ont été synthétisés suivant le même mode opératoire que précédemment et des analyses satisfaisantes ont été obtenus (Schéma 9).

Keywords