Kelly Maurent

Corinne Vanucci-Bacqué

Michel Baltas

Anne Nègre-Salvayre

Nathalie Augé

Florence Bedos-Belval

Maurent Kelly

Synthesis and Biological Evaluation of Diarylheptanoids as Potential Antioxidant and Anti-inflammatory Agents

Keywords: Diarylheptanoid, macrocycle, antioxidant, anti-inflammatory activity

Introduction

Inflammation, one of the most important biological protective responses to tissue damage or microbial invasion, is able to induce cell injury, releasing pro-inflammatory mediators. Inflammation is associated with a large variety of human diseases such as rheumatoid arthritis, inflammatory bowel disease, neurodegenerative disorders, cancer and atherosclerosis [START_REF] Krishnamoorthy | Inflammation and disease progression[END_REF]. Macrophages play a major role in the inflammatory response, by producing reactive oxygen species (ROS), reactive nitrogen species (RNS), and cytokines such as interleukin-1β (IL-1ß), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), prostaglandin (PGE2) and the inflammatory mediator nitric oxide (NO) [START_REF] Curi | A past and present overview of macrophage metabolism and functional outcomes[END_REF]. Nitric oxide is a major signaling agent with a short half-life and huge signaling properties [START_REF] Culotta | NO news is good news[END_REF]. NO is produced by several nitric oxide synthases (NOS), particularly e-NOS, which is constitutively expressed by endothelial cells, producing NO in the vascular wall [START_REF] Heiss | Central Role of eNOS in the Maintenance of Endothelial Homeostasis[END_REF]. At low concentrations, NO exerts various properties such as vasodilation, alongside anti-aggregant and protective properties in physiological and pathological processes. In contrast, large amounts of NO can be produced in response to inflammatory agents by the inducible NO synthase (iNOS) [START_REF] Wu | Nitric Oxide Modulates Pro-and Anti-inflammatory Cytokines in Lipopolysaccharide-Activated Macrophages[END_REF][6] [START_REF] Macmicking | Nitric Oxide and Macrophage Function[END_REF]. This NO, combined with the superoxide anion O2°-, forms peroxynitrite which is very harmful and toxic [START_REF] Macmicking | Nitric Oxide and Macrophage Function[END_REF] [START_REF] Schmidt | Regulation and subcellular location of nitrogen oxide synthases in RAW264.7 macrophages[END_REF].

ROS are key-players of the proinflammatory signaling evoked by cytokines, LPS and stress-inducing agents involved in the progression of inflammatory diseases [START_REF] Lee | Ethyl acetate extract from Asparagus cochinchinensis exerts anti-inflammatory effects in LPS-stimulated RAW264.7 macrophage cells by regulating COX-2/iNOS, inflammatory cytokine expression, MAP kinase pathways, the cell cycle and anti-oxidant activity[END_REF][10] [START_REF] Ning | Neurodegenerative changes and neuroapoptosis induced by systemic lipopolysaccharide administration are reversed by dexmedetomidine treatment in mice[END_REF][12] [START_REF] Tabares-Guevara | Natural Biflavonoids Modulate Macrophage-Oxidized LDL Interaction In Vitro and Promote Atheroprotection In Vivo[END_REF]. Inflammation and oxidative stress are inextricably linked, with complex feed-forward and feedback loops involved in the progression of chronic inflammatory diseases [START_REF] Biswas | Does the Interdependence between Oxidative Stress and Inflammation Explain the Antioxidant Paradox?[END_REF]. Consequently, new therapeutic strategies based on agents sharing both antioxidant and anti-inflammatory properties should be helpful to counter the development of chronic inflammatory diseases. A large number of drugs targeting the inflammatory responses are already available, including steroidal or nonsteroidal anti-inflammatory drugs. However many agents exhibit deleterious side effects, which reduces their interest as prolonged therapeutic applications, and raises the need of alternative non-toxic therapeutic strategies.

Polyphenols are naturally present in plants and exhibit many biological properties, among them the capacity to reduce inflammation [START_REF] Sarkar | Management of Inflammation by Natural Polyphenols: A Comprehensive Mechanistic Update[END_REF]. Phenolic compounds and flavonoids [START_REF] Kumar | Chemistry and Biological Activities of Flavonoids: An Overview[END_REF] can interact with ROS/RNS and thus disrupt chain reaction before cell viability is really affected [START_REF] Hussain | Oxidative Stress and Inflammation: What Polyphenols Can Do for Us?[END_REF]. Among polyphenols, diarylheptanoids, a small class of plant secondary metabolites, consisting of two aromatic rings joined by a seven carbon chain and with various substituents, display strong antioxidant and anti-inflammatory properties [START_REF] Mccalmont | Investigation into the structure?activity relationship of novel concentration dependent, dual action T-type calcium channel agonists/antagonists[END_REF] [START_REF] Rajaganapathy | Molecular basis of the anti-inflammatory potential of a diarylheptanoid in murine macrophage RAW 264.7 cells[END_REF]. This family of compounds can be further subdivided into linear 1,7-diarylheptanoids, such as the well-known curcumin (Fig. 1), and cyclic diarylheptanoids represented by meta,meta-bridged biphenyls and meta,para-bridged diphenyl ethers.

Fig. 1. Structure of curcumin and tedarene A

Among them, we recently synthesized tedarene A (Fig. 1) [START_REF] Maurent | Total Synthesis of Tedarene A[END_REF], a phenolic diarylether macrocycle isolated from a marine sponge, which was reported to significantly inhibit NO production induced by LPS in J774 macrophages [START_REF] Costantino | Tedarenes A and B: Structural and Stereochemical Analysis of Two New Strained Cyclic Diarylheptanoids from the Marine Sponge Tedania ignis[END_REF]. However, preliminary studies indicated that efficient tedarene A concentrations were partly toxic for macrophages RAW 264.7 cells (see below), perhaps due to the presence of a highly reactive dienic system on the heptanoid chain. This prompted us to design new series of diarylheptanoid analogues of tedarene A, by replacing the dienic chemical functionality embedded in the seven atom chain.

The heptanoid chain was modified to introduce various pharmacophore functions, to decrease the cytotoxicity and modulate the physicochemical and biological properties by comparison with tedarene A. This natural diarylether heptanoid features a unique aliphatic chain which makes it highly lipophilic (Clog P = 6.03) and non-druggable. In order to find therapeutic agents with improved drug-like properties, we introduced hydrogen bond donor and/or acceptor functions.

An allylic alcohol moiety was first inserted in the carbon chain (Fig. 2, linker a) to increase the seven carbon chain flexibility compared to tedarene A. An amide function (Fig. 2, linker b), present in 25% of known drugs [START_REF] Montalbetti | Amide bond formation and peptide coupling[END_REF] was secondly integrated. Then, an exocyclic additional primary amine group was introduced at the -position to the amide function (Fig. 2, linker c). In order to modify the macrocycle strains, we envisioned to embed an extra cyclic moiety on the heptanoid chain. The imidazolidine-2,4-dione pattern (Fig. 2, linker d), found in many biological active compounds, was identified as a valuable pharmacophore [START_REF]Recent Developments in Hydantoin Chemistry[END_REF]. Finally, 1,2,3-triazole (Fig. 2, linker e) was selected as a linker displaying a bioisosteric effect, especially on peptide linkages and double bonds [START_REF] Dheer | Medicinal attributes of 1,2,3-triazoles: Current developments[END_REF].

Herein we report the design and synthesis of phenolic or O-methylated diarylether heptanoid macrocycles 1 and 2, as analogues of tedarene A, as well as their corresponding linear analogues 3, to probe the influence of the macrocyclic core on antioxidant and anti-inflammatory activities (Fig. 2). The antioxidant and antiinflammatory properties of these newly synthetized diarylheptanoids were investigated on their ability to block the generation of intracellular ROS, the production of nitrites, and the expression of IL-1 and IL-6 cytokine mRNAs, evoked by LPS in RAW 264.7 murine macrophages, in order to identify effective agents exhibiting dual biological capacities.

Fig. 2.

Design strategy of a new series of tedarene A analogues.

Results and discussion

Chemistry

The envisioned general retrosynthetic approach to obtain the macrocyclic structure involved an intramolecular Ullmann cyclisation of the corresponding linear bromo phenols. This approach allowed us to gain access to the macrocyclic phenolic and Omethylated derivatives 1 and 2, and to the linear phenols 3, in order to evaluate their biological activities (Fig. 2).

Macrocyclic and linear diaryl heptanoids 1a, 2a and 3a, displaying an allylic alcohol function, were prepared as previously reported as they are intermediates encountered during the course of the total synthesis of tedarene A [START_REF] Maurent | Total Synthesis of Tedarene A[END_REF].

Heptanoid linkers displaying an amide moiety (linkers b, c and d, Fig. 2) were obtained via a peptide-type coupling between a common phenylpropylamine 6 and an appropriate phenylpropanoic acid. Amine 6 was obtained by standard regioselective monobromination of the aromatic ring of amine 5 in 60% yield [START_REF] Mccalmont | Investigation into the structure?activity relationship of novel concentration dependent, dual action T-type calcium channel agonists/antagonists[END_REF]. Condensations Macrocycles were obtained by intramolecular Ullmann cyclisation. This reaction performed in the presence of a copper species in basic medium requires long reaction times and high temperatures [START_REF] Sambiagio | Copper catalysed Ullmann type chemistry: from mechanistic aspects to modern development[END_REF]. Heating can be achieved under conventional conditions or under microwave irradiation, which is known to allow shorter reaction times and higher yields [START_REF] Shen | Microwave-assisted synthesis of macrocycles via intramolecular and/or bimolecular Ullmann coupling[END_REF]. As a result, the target macrocycles were obtained by microwave-assisted intramolecular Ullmann coupling.

Macrolactam 2b was directly obtained in 80% yield under standard conditions starting from bromophenol 3b in the presence of copper(II) oxide and potassium carbonate in pyridine at 150°C for 5 h under microwave irradiation (Scheme 2, A).

In order to avoid side reactions stemming from the reactivity of the tert-butoxycarbonyl group of diarylheptanoid 10, the carbamate function was removed by acidic treatment.

The resulting amine 3c was rapidly converted to macrocycle 2c in 40% yield via Ullmann cyclisation under the same conditions as above (MW, 150°C, CuO/K2CO3 in pyridine) (Scheme 2, B).

Scheme 2.

Reagents and conditions: a) CuO, K2CO3, pyridine, MW, 150°C, 5 h; b) BBr3, CH2Cl2, 2 h; c) HCl/dioxane, 45°C, 30 min.

The access to the 3,5-disubstituted hydantoin (imidazolidine-2,4-dione) moiety was efficiently accomplished in a single step cyclisation of the N-Boc protected -amino amide 11 in the presence of trifluoromethanesulfonic anhydride and pyridine at room temperature [START_REF] Liu | Synthesis of Highly Substituted Imidazolidine-2,4-dione (Hydantoin) through Tf 2 O-Mediated Dual Activation of Boc-Protected Dipeptidyl Compounds[END_REF]. This reaction was carried out starting from the tert-butyldimethylsilyl (TBS) protected phenol in order to avoid the formation of a triflate derivative, and gave the expected 1,7-diarylheptanoid 12 in 81% yield. After desilylation with tetra-nbutylammonium fluoride (TBAF), the linear bromophenol 3d was subjected to Ullmann cyclisation conditions under microwave heating. When accomplished in the presence of the CuO/K2CO3 system, the reaction led to the target compound 2d in only 10% yield. The use of a copper (I) bromide dimethylsulfide complex and sodium hydride as base raised this yield to 53% (Scheme 3) [START_REF] Boger | Intramolecular Ullmann condensation reaction: an effective approach to macrocyclic diaryl ethers[END_REF]. Huisgen's cycloaddition between azide 13 and alkyne 14 (Scheme 4). Bromo azide 13 was prepared in three steps from commercially available 2-(4-methoxyphenyl)ethan-1-ol, after monobromination of the aromatic ring, mesylation and substitution [START_REF] Sviridov | Azidosubstituted arylboronic acids: synthesis and Suzuki-Miyaura crosscoupling reactions[END_REF].

Alkyne 14 was obtained from 4-hydroxybenzaldehyde via a known three-step sequence [START_REF] Keilitz | Enantioselective Rh-Catalyzed Domino Transformations of Alkynylcyclohexadienones with Organoboron Reagents[END_REF].

Biological evaluation

Cell viability assay

The biological properties of the synthesized agents were investigated on murine RAW 264.7 macrophages which are suitable cellular models for evaluating inflammation and the protective effect of drugs [START_REF] Chen | Anti-Inflammatory and Antioxidative Effects of Propofol on Lipopolysaccharide-Activated Macrophages[END_REF]. We first evaluated the "self" toxicity of each compound using Trolox as referent antioxidant. The cell viability was evaluated on RAW 264.7 macrophages exposed to the different agents, using the MTT test, as previously reported [START_REF] Bouguerne | Antiatherogenic effect of bisvanillyl-hydralazone, a new hydralazine derivative with antioxidant, carbonyl scavenger, and antiapoptotic properties[END_REF]. For this screening, we have chosen to test the agents at a 30 µM concentration, as the previous report by Costantino and coworkers [START_REF] Costantino | Tedarenes A and B: Structural and Stereochemical Analysis of Two New Strained Cyclic Diarylheptanoids from the Marine Sponge Tedania ignis[END_REF] had shown that tedarene A is efficient at 30 µM against NO production, whereas lower concentrations are not active.

We found that tedarene A is toxic at 30 µM for RAW 264.7 macrophages, with a residual cell viability of less than 60%, after 18h incubation (Fig. 3) and a clear dosedependent toxicity when compared to the untreated control (Supporting information, Supplemental Fig. I). Likewise, compound 3a was toxic at 30 µM, for macrophages, when compared to the untreated control. Note that no toxicity was observed in the first hours of incubation with these agents. All the other compounds were not toxic (cell viability comparable to that of the untreated control) at 30 µM (Fig. 3).

Inhibition of intracellular ROS generated by LPS.

We then checked the ability of the newly synthetized compounds to inhibit the intracellular ROS increase evoked by LPS in RAW 264.7. Indeed, previous reports have shown that LPS rapidly stimulates the production of intracellular ROS, and this can be inhibited by antioxidants such as curcumin [START_REF] Zhong | Curcumin alleviates lipopolysaccharide induced sepsis and liver failure by suppression of oxidative stress-related inflammation via PI3K/AKT and NF-κB related signaling[END_REF][11] [START_REF] Park | Heat-Processed Scutellariae Radix Protects Hepatic Inflammation Through the Amelioration of Oxidative Stress in Lipopolysaccharide-Induced Mice[END_REF]. For this purpose, we used the ROS-sensitive probe H2DCFDA-AM (Fig. 4). As expected, LPS stimulated intracellular ROS production, which was significantly increased after 4h incubation with RAW 264.7 (by comparison with the untreated control). Trolox, used as reference antioxidant, dose-dependently inhibited the intracellular ROS production evoked by LPS (30 µM < IC50 < 50 µM, Supporting information, Supplemental Fig.

II). Tedarene

A significantly inhibited ROS production at 30 µM (Fig. 4), but had no effect at lower concentrations (Supporting information, Supplemental Fig. II).

The effect of the new agents on ROS production was compared to that evoked by LPS alone (*) and to that of tedarene A used as reference compound (#). Among the 15 tested agents, 6 were found to be significantly efficient. More precisely, the phenolic allylic alcohol 1a and at a lesser extent, the diarylheptanoid 3a, significantly inhibited ROS production at 30 µM. The phenolic amide-type agents 1b and 3b, were significantly protective, but their effect was weaker than that elicited by other agents.

The tyrosine derived compounds 1-3c, which possess an additional primary amine function on the seven atom chain, exhibited a different ROS inhibition activity to that of the amide analogues 1-3b. A loss of antioxidant activity of phenolic macrocycle 1c, compared to amide 1b, was observed. The phenolic linear agent 3c, was comparable to that of tedarene A, and was better than that of its amide counterpart 3b. The phenolic linear agent 3c, exhibited a strong inhibitory effect, higher than tedarene A and trolox, and better than that of its amide counterpart 3b. Finally, the non-phenolic macrocycle 2c significantly inhibited ROS production, with an efficacy comparable to tedarene A.

In this case, the lack of a phenolic function was compensated by the presence of the primary amine.

The imidazolidine-2,4-dione and 1,2,3-triazole derivatives, containing a five-membered ring in the heptanoid chain, exhibited no antioxidant ability even with the presence of phenol groups which is therefore not sufficient to induce this activity. Consequently, an additional cyclic moiety on the heptanoid chain does not appear to be relevant in the inhibition of intracellular ROS production.

These results point out the inhibitory effect of the agents on intracellular ROS production stimulated by LPS, and their correlation with the cell viability data, particularly those concerning the toxicity of agent 3a. This data allowed us to select five diaryl heptanoids: three macrocyles 1a, 1b and 2c, and two linear bromo phenols 3b and 3c, which were evaluated on inflammation parameters. As for tedarene A, we aimed at verifying the dose-dependent toxicity of the selected agents (Supporting information, Supplemental Fig. I), and their dose-dependent inhibitory effect on ROS production evoked by LPS (Supporting information, Supplemental Fig. II). These agents are not toxic for macrophages up to 30 µM, with slight toxicity between 30 and 50 µM (agents 1a and 3b), and no significant toxicity for the other compounds.

Likewise, dose-response experiments show that all the tested agents significantly block ROS production evoked by LPS, with strong efficacy for the compounds 1a and

Anti-inflammatory activity

Effect of the agents on the nitrite production elicited by LPS

Peroxynitrites and nitrites represent the final products of the NO oxidation pathway.

Thus, determining the level of nitrite NO2 -formation in cell culture medium is indicative of NO production via inflammation. The effect of the newly synthesized compounds 1a, 1b, 3b, 2c and 3c was checked against nitrite production by LPS stimulated RAW 264.7. Nitrite levels were evaluated on the culture medium after 4 h of contact with LPS, in the presence (or absence) of the different agents, using the Griess reaction technique. Tedarene A was used as reference (Fig. 5). Under these conditions, tedarene A was able to inhibit more than 65% of LPS-induced NO production, in agreement with previous reports in J774 cells [START_REF] Costantino | Tedarenes A and B: Structural and Stereochemical Analysis of Two New Strained Cyclic Diarylheptanoids from the Marine Sponge Tedania ignis[END_REF]. Ted. A used as reference, # p<0.05 (annotated in red). ns : non-significant.

All compounds significantly decreased the nitrite levels evoked by LPS (Fig. 5).

Macrocyclic diarylether 1b inhibited nitrite production (around 65%) in the same range as tedarene A. The other derivatives 1a, 3b, 2c and 3c were more efficient than tedarene A, showing more than 80% inhibition, with the most potent being the phenolic macrocycle 1a.

Effect of the compounds on the expression of pro-inflammatory cytokines evoked by LPS

The inflammatory signaling of LPS and other stress-inducing agents results in the production of a variety of cytokines, chemokines, adhesion molecules, and inflammation mediators [START_REF] Chen | Anti-Inflammatory and Antioxidative Effects of Propofol on Lipopolysaccharide-Activated Macrophages[END_REF]. We aimed at investigating whether the new diarylheptanoid agents may block the expression of cytokine IL-1 and IL-6 mRNAs evoked by LPS. As shown in Fig. 6, all compounds significantly blocked the expression of IL-1 and IL-6 mRNAs evoked by LPS, after 4h incubation with macrophages.

Furthermore, almost all the agents were as efficient as tedarene A with 30 to 50% of inhibition on IL-1 mRNAs expression and more than 60% of inhibition on IL-6 mRNA expression.

Conclusion

The aim of this work was to synthesize a series of linear and macrocyclic analogues and test their potential antioxidant and anti-inflammatory efficacy against LPS-induced cellular responses in macrophages. The lead compound tedarene A inhibits LPSinduced ROS and NO production, therefore it presents anti-inflammatory properties.

However, the toxicity of this agent limits its use in biological systems and living organisms. Among the 15 newly synthesized diarylheptanoid agents, five compounds were found to have similar or higher efficacy than tedarene A to block ROS production evoked by LPS, but were devoid of its toxic side effects. Moreover, these agents were as efficient as tedarene A to block the production of nitrites induced by LPS in RAW 264.7 macrophages. Since nitrite generation reflects the production of NO but also its combination to superoxide anion which forms NO2 -, it is likely that these agents inhibit nitrite formation by blocking the production of O2°-, as suggested by the inhibition of ROS production. In addition, all these agents inhibited more efficiently than tedarene A the expression of cytokines mRNAs such as IL-1 and IL-6. It can be expected that these diarylheptanoid agents should inhibit the inflammatory signaling pathways evoked by LPS, such as the activation of inflammasomes NLRP, or the NFB pathway, due to their inhibition by curcumin [34][35]. The important point is that all the five tested linear or macrocyclic agents exhibit antioxidant and anti-inflammatory properties comparable to tedarene A, but are however much less toxic (at the tested concentration), which emphasizes their potential interest for therapeutic purposes.

These activities do not appear clearly correlated to the chemical structure (macrocyclic versus linear) of the agents. Based on these results, further studies aimed at synthesizing more potent anti-inflammatory agents are currently in progress.

Experimental section

4.1. Chemistry

General

Unless otherwise noted, all experiments were carried out under a nitrogen atmosphere.

Solvents (CH2Cl2 and THF) were dried via a purification solvent system MB-SP-800

tert-butyl (S)-(1-((3-(3-bromo-4-methoxyphenyl)propyl)amino)-3-(4-

hydroxyphenyl)-1-oxopropan-2-yl)carbamate [START_REF] Zhong | Curcumin alleviates lipopolysaccharide induced sepsis and liver failure by suppression of oxidative stress-related inflammation via PI3K/AKT and NF-κB related signaling[END_REF]. To a solution of amine [START_REF] Ning | Neurodegenerative changes and neuroapoptosis induced by systemic lipopolysaccharide administration are reversed by dexmedetomidine treatment in mice[END_REF]. To a solution of acid Hz, 1H); 3.17 (dt, J = 6.9, 13.2 Hz, 1H); 3.08 (dt, J = 6.9, 13.5 Hz, 1H), 2.86 (dd, J = 6.9, 13.5 Hz, 1H); 2.76 (dd, J = 6.9, 13.5 Hz, 1H), 2.47-2.42 (m , 2H); 1.72-1.62 (m, 2H). 13

tert-butyl (S)-(1-((3-(3-bromo-4-methoxyphenyl)propyl)amino)-3-(4-((tertbutyldimethylsilyl)oxy)phenyl)-1-oxopropan-2-yl)carbamate

(S)-3-(3-(3-bromo-4-methoxyphenyl)propyl)-5-(4-((tert-butyldimethylsilyl)oxy)

benzyl)imidazolidine-2,4-dione [START_REF] Park | Heat-Processed Scutellariae Radix Protects Hepatic Inflammation Through the Amelioration of Oxidative Stress in Lipopolysaccharide-Induced Mice[END_REF]. To a solution of amide 11 (212 mg, 0.34 mmol) in CH2Cl2 (4 mL) at 0°C was added pyridine (80 µL, 1 mmol). Tf2O (86 µL, 0.51 mmol)

was added slowly and the reaction mixture was allowed to warm to room temperature.

After stirring for 1 h, saturated aqueous NaHCO3 solution was added. The aqueous layer was extracted with CH2Cl2. The combined organic layer was washed with aqueous saturated NaHCO3 solution, water and brine then dried over Na2SO4 and concentrated under reduced pressure. Silica gel column chromatography (CH2Cl2/MeOH = 99:1) provided pure hydantoin 12 (152 mg, 81%) as an orange gum.

D 20 = -67.9 ( c 1.0, CH2Cl2). IR (neat) max : 3286, 1710 cm -1 .

1-(3-bromo-4-methoxyphenethyl)-4-(4-((tert-butyldimethylsilyl)oxy)phenethyl)-

1H-1,2,3-triazole [START_REF] Sarkar | Management of Inflammation by Natural Polyphenols: A Comprehensive Mechanistic Update[END_REF]. To a solution of alcyne 14 [START_REF] Keilitz | Enantioselective Rh-Catalyzed Domino Transformations of Alkynylcyclohexadienones with Organoboron Reagents[END_REF] (540 mg, 2.07 mmol) in a 1/1 THF-H2O mixture (14 mL) were added successively sodium ascorbate (206 mg, 1.03 mmol), CuSO4.5H2O (103 mg, 0.41 mmol) and a solution of azide 13 [START_REF] Sviridov | Azidosubstituted arylboronic acids: synthesis and Suzuki-Miyaura crosscoupling reactions[END_REF] (532 mg, 2.07 mmol) in a 1/1 THF-H2O mixture (4 mL). The reaction mixture was stirred overnight at room temperature. Water was then added and the aqueous layer was extracted with EtOAc. The combined organic layer was washed with water and brine, For the experiments, the cells were incubated in serum-free RPMI1640 medium.

dried

Cell viability assay

Cell cytotoxicity was evaluated by MTT (3-(4,5-dimethylthizol-2-yl)-2,5diphenyltetrazolium bromide) assay as previous reported [START_REF] Bouguerne | Antiatherogenic effect of bisvanillyl-hydralazone, a new hydralazine derivative with antioxidant, carbonyl scavenger, and antiapoptotic properties[END_REF].

Intracellular ROS determination.

Intracellular ROS generation was evaluated by measuring the oxidation of H2DCFDA-AM in the previously reported conditions [START_REF] Bouguerne | Antiatherogenic effect of bisvanillyl-hydralazone, a new hydralazine derivative with antioxidant, carbonyl scavenger, and antiapoptotic properties[END_REF]. The probe was added to the culture medium (5 µM final concentration) 30 min before the end of the experiment. The cells were washed three times with PBS, and the fluorescence was measured as reported (exc 495, em 520 nm). The data are expressed as ratio fluorescence/fluorescence of the LPS-stimulated control.

Nitrite level assays

Nitrite production was quantified in the culture medium using the Griess reaction test.

Briefly, RAW 264.7 cells were pretreated with the compounds for 30 min, then stimulated with LPS (20 ng/mL) for 4 h. The isolated supernatants were mixed with an equal volume of Griess reagent. Nitrite production was determined by measuring the absorbance at 550 nm after 15 minutes of incubation (vs 690nm to remove the background) using a microplate reader (Infinite ® M200 PRO, Tecan).

Scheme 1 .

 1 Scheme 1. Reagents and conditions: a) Br2, AcOH, rt, 18 h; b) EDC, HOBt, NEt3, rt, 5 h in THF for 3b and 10 or 18 h in DMF for 11.

Finally, cyclic diaryletherScheme 3 .

 3 Scheme 3. Reagents and conditions: a) Tf2O, pyridine, CH2Cl2, rt, 1h; b) TBAF, THF, 0°C, 10 min; c) CuBr-DMS, NaH, pyridine, MW, 150°C , 30 min; d) BBr3, CH2Cl2, -78°C to 0°C, 1 h.

Fig. 3 .

 3 Fig. 3. Self-toxicity of diarylheptanoid agents. RAW 264.7 macrophages were incubated with Trolox (Trx), tedarene A (Ted. A) or the other newly synthesized agents (final concentration 30 µM for all the tested agents). The cell viability was evaluated by the MTT assay after 18h incubation at 37°C. The results are expressed as % of the unstimulated control (grey bar). Mean ± SEM of 5 separate experiments. *: Untreated control used as reference, ***p<0.001, ****p<0.0001.

3c.

  The IC50 of the different compounds on ROS inhibition was around 30 µM for tedarene A, Trolox, compounds 2c and 3c, and between 30 and 50 µM for the compounds 1a, 1b and 3b. Further experiments on cytokines were carried out on short periods of time (up to 4h), using a 30 µM concentration for all compounds.

Fig. 4 .

 4 Fig.4. Effect of the diarylheptanoid agents on the intracellular ROS increase evoked by LPS. Intracellular ROS production was measured in RAW 264.7 stimulated for 4h with LPS (20 ng/mL) without (100%, black bar), or with Trolox (Trx), tedarene A (Ted. A) or the different agents (30 µM), in serum-free culture medium. 30 minutes before the end of the experiment, the culture medium was removed and replaced by a medium containing the fluorescent ROS-sensitive H2DCFDA-AM probe (5 µM). After carefully washing the cells in PBS, RAW 264.7 were homogenized in water, and the fluorescence was read as indicated in the Experimental Section. Results were normalized using the fluorescence of LPS-stimulated cells. Mean ± SEM of 6 separate experiments. *: LPS used as reference (annotated in black), *p<0.05; **p<0.01, ***p<0.001, ****p<0.0001 (annotated in black). # : Ted. A used as reference (annotated in red), # p<0.05; ## p<0.01, ### p<0.001 (annotated in red). ns : non-significant.

Fig. 5 .

 5 Fig.5. Effect of the diarylheptanoid agents on LPS-mediated nitrite production. RAW 264.7 cells were pretreated tedarene A (Ted. A) and the agents (30 µM) for 30 min and then treated with LPS (20 ng/mL) for 4h. Results are expressed as percentage nitrite production elicited by LPS. Mean ± SEM of 5 separate experiments. * : LPS used

Fig. 6 .

 6 Fig.6. Effect of the diarylheptanoid agents on the expression of IL-1 and IL-6 mRNA expression evoked by LPS. RAW 264.7 cells were pretreated with tedarene A (Ted. A) or the agents (30 µM) for 30 min and then stimulated by LPS (20 ng/mL) for 4h. In A, expression of IL-1 mRNAs, in B, IL-6. The results are normalized to the reference gene GAPDH, and expressed as ratio/ LPS-stimulated cells. Mean ± SEM of 5 separate experiments. *: LPS used as reference (annotated in black), *p<0.05; **p<0.01, ***p<0.001. # : Ted. A used as reference (annotated in red), ## p<0.01. ns : non-significant.

4. 2 . 5 .

 25 Cytokine mRNA quantification (IL-1 and IL-6) Total RNA was isolated from cells with Tri-reagent RT (Euromedex ® RT-111-50) and retrotranscripted with High-capacity cDNA Reverse Transcription Kit (Applied Biosystems ® , ref: 4374966). mRNA levels were measured by real-time quantitative polymerase chain reaction with Fast SYBR Green Master Mix kit (Applied Biosystems, ref: 4385612). The following primers were used: expression was normalized to GAPDH expression.

4. 2 . 6 .

 26 Statistical Analyses. Results are expressed as mean ± SEM. Statistical analyses were done using Graph Pad Prism 5 for Windows (Graph Pad Software). Parametric tests consisted in Anova test (Dunnet's post hoc). Results were considered significant at P<0.05.

  The reaction mixture was stirred at rt overnight and quenched with water. The aqueous layer was extracted with CH2Cl2 and the combined organic layers were washed with water. The combined aqueous layer was basified to pH = 9 by addition of solid Na2CO3, then extracted with CH2Cl2. The obtained combined

	organic layer was washed with water, brine, dried over Na2SO4 and concentrated
	under reduced pressure to give the expected compound 6 (1.53 g, 60%) as a yellow
	oil, pure enough to be used without further purification. IR (KBr) max : 3364, 1498 cm -
	1 . 1 H NMR (300 MHz, MeOD)  7.37 (d, J = 2.1 Hz, 1H); 7.13 (dd, J = 2.1, 8.4 Hz, 1H);
	6.92 (d, J = 8.4 Hz, 1H); 3.82 (s, 3H); 2.64-2.53 4H); 1.72 (q, J = 7.5 Hz, 2H). 13 C
	NMR (75 MHz, MeOD)  155.5; 137.1; 134.0; 129.5; 113.3; 112.3; 56.7; 42.0; 35.8;
	32.9. HRMS (DCI, CH4) m/z calcd for C10H14NOBr [M+H] + : 244.0337, found: 244.0347.
	4.1.3.	N-(3-(3-bromo-4-methoxyphenyl)propyl)-3-(4-hydroxyphenyl)propanamide
	J = 8.4 Hz, 1H); 6.71-6.66 (m, 2H); 3.83 (s, 3H); 3.12 (t, J = 6.9 Hz, 2H); 2.81 (t, J =
	recorded on a Xevo G2 QTOF (Waters) instrument. Reactions were monitored by TLC 7.3 Hz, 2H); 2.48-2.49 (m, 4H); 1.68 (q, J = 7.2 Hz, 2H). 13 C NMR (75 MHz, MeOD) 
	on silica gel Alugram ® Xtra SIL G/UV254. Column chromatography was performed on 175.4; 156.8; 136.7; 134.0; 132.8; 130.4; 129.6; 116.2; 113.2; 112.3; 56.7;39.8; 39.2;
	Machery-Nagel silica gel 0.063-0.2 mm. Reactions utilizing microwave technology 32.7; 32.2; 32.1. HRMS (DCI, CH4) m/z calcd for C19H23NO3Br [M+H] + : 392.0861,
	were conducted in a CEM Discover Benchmate microwave reactor (model no. found: 392.0868.
	908010).

(MBRAUN). Melting points (Mp) were obtained on a Buchi apparatus and are uncorrected. Measurements above 200°C were not possible with this apparatus. IR spectra were recorded on a Thermo Nicolet Nexus spectrometer. NMR spectra were recorded on Brucker Avance 300 MHz spectrometer. The NMR spectra were acquired in CDCl3, CD3OD or DMSO-d6, and the chemical shifts were reported in parts per million (ppm) with the solvent residual peaks as references. Signals are described as follow: s, singlet; brs, broad signal; d, doublet; t, triplet; m, multiplet. HRMS data were

4.1.2. 3-(3-bromo-4-methoxyphenyl)propan-1-amine

[START_REF] Mattila | Nitric Oxide Synthase: Non-Canonical Expression Patterns[END_REF]

.To a solution of amine 5 (1.72 g, 10.4 mmol) in glacial AcOH (19 mL) was added dropwise a solution of Br2 (0.64 mL, 12.5 mmol) in AcOH (15 mL).

(3b).To a solution of amine 6 (317 mg, 1.3 mmol) in anhydrous THF (3 mL) at room temperature were added successively the acid 7 (200 mg, 1.2 mmol), HOBt (16 mg, 0.12 mmol), EDC (202 mg, 1.3 mmol) and NEt3 (167 µL, 1.2 mmol). The reaction mixture was stirred at room temperature for 5 h, then worked up by addition of water.

The aqueous layer was extracted with EtOAc. The combined organic layer was washed with saturated aqueous NaHCO3 solution, water and brine, then dried over Na2SO4 and concentrated under reduced pressure. The expected compounds 3b (428 mg, 75%) was obtained as a colorless solid, pure enough to be used without further purification. Mp : 75.5-77.5°C. IR (KBr) max : 3331, 1640, 1564 cm -1 . 1 H NMR (300 MHz, MeOD)  7.33 (d, J = 2.1 Hz, 1H); 7.08 (dd, J = 2.1, 8.4 Hz, 1H); 7.04-7.00 (m, 2H); 6.92 (d,

  (394 mg, 1.4 mmol), HOBt (19 mg, 0.14 mmol), EDC (248 mg, 1.6 mmol and NEt3 (223 µL, 1.4 mmol). The reaction mixture was stirred at room temperature for 5 h, then worked up by addition of water. The aqueous layer was extracted with EtOAc.

	The combined organic layer was washed with saturated aqueous NaHCO3 solution,
	water and brine, then dried over Na2SO4 and concentrated under reduced pressure.
	The expected compounds 10 (676 mg, 83%) was obtained as a light yellow gum, pure
	enough to be used without further purification. D 20 = + 10.5 (c 1.0, MeOH). IR (neat)
	max : 3340, 1674 cm -1 . 1 H NMR (300 MHz, MeOD)  7.35 (d, J = 2.1 Hz, 1H); 7.10
	(dd, J = 2.1, 8.4 Hz, 1H); 7.06-7.03 (m, 2H); 6.93 (d, J = 8.4 Hz, 1H); 6.72-6.68 (m,
	2H); 4.19-4.14 (m, 1H); 3.83 (s, 3H); 3.19-3.04 (m, 2H); 2.92 (dd, J = 6.9, 13.5 Hz, 1H);
	2.75 (dd, J = 8.1, 13.5 Hz, 1H), 2.49-2.44 (m, 2H); 1.73-1.63 (m, 2H); 1.39 (s, 9H). 13 C
	NMR (75 MHz, MeOD)  174.4; 157.5; 157.3; 155.6; 136.7; 134.3; 131.3; 129.6; 129.1;
	116.2; 113.2; 112.3; 80.6; 57.9; 56.6; 39.7; 38.7; 32.7; 32.1; 23.7. HRMS (DCI, CH4)
	m/z calcd for C19H23NO3Br [M+H]

6 (386 mg, 1.6 mmol) in anhydrous THF (4 mL) at room temperature were added successively the acid 8 + : 507.1495, found: 507.1470.

  over Na2SO4 and concentrated under vacuum. Silica gel column chromatography Following the general procedure, phenol 3b (31 mg, 8 10 -2 mmol) was heated for 5 h. The aqueous layer was extracted with CH2Cl2. The combined organic layer was washed with water, brine and dried over Na2SO4 and concentrated under reduced pressure. , 1710 cm -1 . 1 H NMR (300 MHz, DMSO-d6)  : 9.17 (s, OH) ; 8.27 (s, NH) ; 7.36 (dd, J = 8.2, 2.0 Hz, 1H); 7.19 (dd, J = 8.4, 2.0 Hz, 1H); 7.11 (dd, J = 8.2, 2.5 Hz, 1H); 6.90 (dd, J = 8.4, 2.5 Hz, 1H); 6.58 (d, J = 7.8 Hz, 1H); 6.40 (d, J = 7.8 Hz, 1H); 5.54 (bs, 1H); 4.44 (t, J = 2.7 Hz, NH); 3.27-3.18 (m, 2H); 3.06-2.98 (m, 2H); 2.46-2.25 (m, 2H); 2.02-1.86 (m, 1H); 0.81-0.65 (m, 1H). 13 C NMR (75 MHz, DMSO-d6) 173.2; Following the general procedure, compound 2e (70 mg, 0.218 mmol) was stirred at 0°C for 1h. Silica gel column chromatography (CH2Cl2/MeOH = 97:3) afforded pure compound 1e (54 mg, 80% yield) as a colorless solid. Mp > 200°C. D 20 = + 2.5 ( c 0.4, MeOH). IR (neat) max : 3411, 1529 cm -1 . 1 H NMR (300 MHz, DMSO-d6)  7.28 (s, 1H); 7.10-7.07 (m, 2H); 6.79-6.76 (m, 2H); 6.72 (d, J = 8.1 Hz, 1H); 6.61 (dd, J = 8.1, 2.1 Hz, 1H); 4.78 (d, J = 2.1 Hz, 1H) ; 4.25-4.21 (m, 2H); 3.08-3.03 (m, 2H); 3.0-

	1H); 6.78-6.73 (m, 2H); 4.47 (t, J = 7. Hz, 2H); 3.05 (t, J = 7.0 Hz, 2H); 2.93-2.79 (m, 4.1.11.1. 1 6 -methoxy-2-oxa-7-aza-1(1,3),3(1,4)-dibenzenacyclodecaphan-6-one (2b). 3.09-3.01 (m, 4H); 2.96-2.92 (m, 2H). 13 C NMR (75 MHz, DMSO-d6)  153.8; 150.7;
	4H); 0.97 (s, 9H); 0.17 (s, 6H). 13 C NMR (75 MHz, CDCl3)  154.9; 153.9; 147.1; 133.9; 146.9; 140.6; 138.0; 131.6; 131.0; 124.4; 122.7; 122.0; 115.2; 112.4; 55.7; 50.4; 32.8;
	133.4; 130.7; 129.4; 128.8; 121.4; 119.9; 112.1; 111.7; 56.3; 51.4; 35.6; 34.8; 27.6; Silica gel column chromatography (CH2Cl2/MeOH = 98:2) afforded pure compound 2b 32.4; 25.8. HRMS (DCI, CH4) m/z calcd for C19H20N3O2 [M+H] + : 322.1556, found: 4.1.13.1. 1 6 -hydroxy-2-oxa-7-aza-1(1,3),3(1,4)-dibenzenacyclodecaphan-6-one(1b).
	25.7; 18.2; -4.4. HRMS (DCI, CH4) m/z calcd for C25H35N3O2Br [M+H] + : 516.1682, (20 mg, 80% yield) as a colorless solid. Mp : 166-168 °C. IR (neat) max : 3280, 1671 322.1560. Following the general procedure, compound 2b (72 mg, 0.23 mmol was stirred at 0°C
	found: 516.1661. cm -1 . 1 H NMR (300 MHz, MeOD)  7.27-7.23 (m, 2H); 6.99-6.95 (m, 2H); 6.89 (d, J = for 4 h. Silica gel column chromatography (CH2Cl2/MeOH = 96:4) afforded pure
	8.1 Hz, 1H); 6.66 (dd, J = 8.1, 2.1 Hz, 1H); 5.48 (d, J = 2.1 Hz, 1H); 3.90 (s, 3H); 2.99-4.1.12. (1 4 S)-5 6 -methoxy-4-oxa-1(4,1)-imidazolidina-3(1,4),5(1,3)-compound 1b (44 mg, 48% yield) as a beige solid. D 20 = +0.85 (c 0.48, MeOH). Mp 157.2; 156.4; 151.0; 143.1; 133.5; 132.4; 131.9; 131.8; 123.7; 123.2; 119.9; 116.7;
	4.1.10. 2.95 (m, 2H); 2.73 (t, J = 6.9 Hz, 2H); 2.52-2.48 (m, 2H); 2.44-2.40 (m, 2H); 1.62 (q, J 4-(2-(1-(3-bromo-4-methoxyphenethyl)-1H-1,2,3-triazol-4-yl)ethyl)phenol dibenzenacyclooctaphane-1 2 ,1 5 -dione (2d). A mixture of phenol 3d (35 mg), NaH (5 > 200 °C. IR (neat) max : 3300, 1622 cm -1 . 1 H NMR (300 MHz, MeOD)  7.26-7.22 (m, 115.2; 57.5; 39.2; 34.4; 32.4; 31.5. HRMS (DCI, CH4) m/z calcd for C19H19N2O4 [M+H] + :
	(3e).To a solution of triazole 15 (890 mg, 1.72 mmol) in anhydrous THF (20 mL) at 0°C = 6.6 Hz, 2H). 13 C NMR (75 MHz, MeOD)  175.2; 157.5; 152.8; 147.9; 138.9; 134.5; mg) and CuBr.DMS (164 mg) in dry pyridine (4 mL) was heated at 150°C under 2H); 7.0-6.97 (m, 2H); 6.73 (d, J = 8.1 Hz, 1H); 6.55 (dd, J = 8.1, 2.1 Hz, 1H); 5.48 (d, 339.1345, found 339.1336.
	was added TBAF (1M in THF, 3.45 mL, 3.45 mmol). The reaction mixture was stirred 132.0; 124.4; 122.8; 117.2; 114.1; 56.9; 39.8; 39.4; 32.9; 30.3; 27.6. HRMS (DCI, CH4) microwave irradiation in a sealed tube for 30 min. The reaction mixture was cooled to J = 2.1 Hz, 1H); 2.99-2.95 (m, 2H); 2.71 (t, J = 7.1 Hz, 2H); 2.50-2.46 (m, 2H); 1.66-
	at 0°C for 3h and quenched with saturated aqueous NaHCO3 solution. The aqueous layer was extracted with EtOAc and the combined organic layer was washed with saturated aqueous NaHCO3 solution, water and brine, dried over Na2SO4 and concentrated under reduce pressure. Pure phenol 3e (574 mg, 83%) was obtained by recrystallization in MeOH as a colorless solid. Mp : 140 °C. IR (neat) max : 3432, 1613 cm -1 . MHz, DMSO-d6)  155.4; 154.0; 146.2; 133.0; 131.4; 131.3; 129.2; 129.1; 121.9; 115.0; 112.5; 110.4; 56.1; 50.3; 34.4; 34.2; 27.3. HRMS (DCI, CH4) m/z calcd for C19H21N3O2Br [M+H] + : 402.0817, found: 402.0803. 4.1.11. Ullmann cyclisation: General procedure for the synthesis of compounds 2b, 2c and 2e. A mixture of phenol (1 equiv), K2CO3 (2 equiv) and CuO (2.5 equiv) in dry pyridine (2 10 -2 M) was heated at 150°C under microwave irradiation in a sealed tube. The reaction mixture was cooled to rt and concentrated under reduced pressure. The residue was dissolved in EtOAc and neutralized by addition of 10% aqueous NaHSO3 solution. The m/z calcd for C19H22NO3 [M+H] + : 312.1600, found: 312.1595. 4.1.11.2.(S)-5-amino-16-methoxy-2-oxa-7-aza-1(1,3),3(1,4)-dibenzenacyclodecaphan-6-one (2c). Following the general procedure, phenol 3c (62 mg, 1.4 10 -4 mmol) was heated for 30 min. Silica gel column chromatography (CH2Cl2/MeOH = 92:8) afforded pure compound 2c (19 mg, 41% yield) as a yellow gum.D 20 = -43.9 ( c 1.0, MeOH). IR (neat) max : 3343, 3328, 1658 cm -1 . 1 H NMR (300 MHz, MeOD)  7.35 (dd, J = 8.4, 2.2Hz, 1H); 7.19 (dd, J = 8.2, 2.5 Hz, 1H); 7.10 (dd, J = 8.3, 2.2 Hz, 1H); 6.91 (d, J = 8.3 Hz, 1H); 6.79 (dd, J = 8.3, 2.4 Hz, 1H); 6.68 (dd, J = 8.2, 2.2 Hz, 1H); 5.53 (d, J = 2.1 Hz, 1H); 3.90 (s, 3H); 3.64 (brs, NH); 3.51 (dd, J = 10.6, 5.5 Hz, 1H); 3.16 (dd, J = 12.2, 5.5 Hz, 1H); 3.06 (dt, J = 13.8, 7.9 Hz, 1H); 2.69 (dd, J = 12.2, 10.6 Hz, 1H); 2.62 (ddd, J = 16.0, 8.0 Hz, 3.1 Hz, 1H); 2.49-4.31 (m, 1H); 2.41-2.32 (m, 1H); 1.85-1.70 (m, 1H); 1.64-1.46 (m, 1H). 13 C NMR (75 MHz, MeOD) : 176.0; 158.1, 152.7; 148.0; 135.7; 134.0; 133.2; 131.4; 124.8; 124.2; 123.1; 117.3; 114.3; 58.8; 56.9; 42.7 38.9; 29.9; 26.6. HRMS (DCI, CH4) m/z calcd for C19H22N2O3 [M] + : 326.1630, found : 326.1622. 4.1.11.3. rt and concentrated under reduced pressure. The residue was dissolved in EtOAc and 1.57 (m, 2H); 1.62 (q, J = 6.6 Hz, 2H). 13 C NMR (75 MHz, MeOD) 175.2; 157.8; 4.1.13.4. (Z)-6 1 H-2-oxa-6(4,1)-triazola-1(1,3),3(1,4)-dibenzenacyclooctaphan-16-ol neutralized by addition of 10% aqueous NaHSO3 solution. The aqueous layer was extracted with EtOAc and the combined organic layers were washed with 10% aqueous NaHSO3 solution, water and brine, then dried over Na2SO4 and concentrated under reduced pressure. The crude residue was purified by silica gel column 8.3, 2.2 Hz, 1H); 7.09 (dd, J = 8.2, 2.5 Hz, 1H); 6.87 (dd, J = 8.3, 2.5 Hz, 1H); 6.75 (d, 151.3; 144.8; 138.7; 132.8; 131.8; 124.4; 123.0; 117.3; 117.1; 39.8; 39.3; 32.9; 30.2; 27.2. HRMS (DCI, CH4) m/z calcd for C18H20NO3 [M+H] + : 298.1443, found: 298.1438. 4.1.13.2. (S)-5-amino-16-hydroxy-2-oxa-7-aza-1(1,3),3(1,4)-dibenzenacyclodecaphan-6-one(1c). Following the general procedure, compound 2c (29 mg, 0.089 mmol) was stirred at 0°C for 2h. Silica gel column chromatography (CH2Cl2/MeOH = 90:10) afforded pure compound 1c (19 mg, 68% yield) as a light (1e). 2.93 (m, 4H) . 13 C NMR (75 MHz, DMSO-d6)  154.3; 149.7; 144.7; 143.7; 137.8; yellow gum. D 20 = -38.4 (c 1.0, MeOH). IR (neat) max : 3411, 3281, 1648 cm -1 . 1 H 131.0; 129.8; 124.7; 122.9; 122.3; 116.1; 115.7; 50.8; 32.8; 32.4; 25.8. HRMS (DCI, J = 8.0 Hz, 1H); 6.55 (dd, J = 8.0, 2.1 Hz, 1H); 4.71 (d, J = 2.1 Hz, 1H); 4.44 (dd, J = NMR (300 MHz,MeOD)  7.35 (dd, J = 8.3, 2.2Hz, 1H); 7.15 (dd, J = 8.5, 2.1 Hz, 1H); CH4) m/z calcd for C18H18N3O2 [M+H] + : 308.1399, found: 302.1402. 4.2, 3.2 Hz, 1H); 3.87 (s, 3H); 3.44 (ddd, J = 14.1, 5.3, 2.1 Hz, 1H); 3.36 (dd, J = 14.1, 7.11 (dd, J = 8.2, 2.5 Hz, 1H); 6.81 (dd, J = 8.3, 2.5 Hz, 1H); 6.76 (d, J = 8.1 Hz, 1H); 3.2 Hz, 1H); 3.18 (ddd, J = 14.0, 12.8, 1.5 Hz, 1H); 3.14 (dd, J = 14.3, 4.2 Hz, 1H); 6.56 (dd, J = 8.1, 2.1 Hz, 1H); 5.52 (d, J = 2.1 Hz, 1H); 3.60-3.50 (m, 1H); 3.18 (dd, J 4.2. Biological experiments. 2.54 (dd, J = 13.8, 8.4 Hz, 1H); 2.40 (ddd, J = 14.4, 10.2, 8.2 Hz, 1H); 2.07-1.93 (m, = 12.2, 5.6 Hz, 1H); 3.07 (dt, J = 13.7, 7.8 Hz, 1H); 2.71 (dd, J = 11.9, 10.7 Hz, 1H); 1H); 0.96-0.83 (m, 1H). 13 C NMR (75 MHz, MeOD) 175.5; 159.8; 158.6; 153.7; 147.4; 2.60 (ddd, J = 16.2, 7.7, 3.1 Hz, 1H); 2.44 (dd, J = 10.0, 3.1 Hz, 1H); 2.43-2.29 (m, 4.2.1. Cell culture 137.1; 133.8; 133.1; 133.0; 125.0; 124.4; 121.0; 118.4; 112.9; 59.6; 56.8; 40.9; 35.9; 1H); 1.85-1.72 (m, 1H); 1.58-1.45 (m, 1H). 13 C NMR (75 MHz, MeOD)  175.4; 158.5, RAW 264.7 murine macrophages were obtained from American Type Culture 33.9; 33.2. HRMS (DCI, CH4) m/z calcd for C20H21N2O4 [M+H] + : 353.1501, found: 151.3; 145.1; 135.4; 133.2; 132.4; 131.2; 124.9; 124.4; 123.4; 117.6; 117.3; 58.5; 42.2; Collection (Manassas, Virginia), and were cultured in Dulbecco's modified Eagle's 353.1487. 38.9; 29.8; 26.4. HRMS (DCI, CH4) m/z calcd for C18H20N2O3 [M+H] + : 313.1552, found medium (DMEM) supplemented with 10% heat inactivated fetal calf serum in a 37°C (Z)-1 6 -methoxy-6 1 H-2-oxa-6(4,1)-triazola-1(1,3),3(1,4)-dibenzenacyclooctaphane (2e). Following the general procedure, phenol 3e (30 mg, : 313.1567. humidified incubator containing 5% CO2.
	aqueous layer was extracted with EtOAc and the combined organic layers were 4.1.13. O-demethylation : General procedure for the synthesis of compounds 1b-e. 7.4 10 -5 mmol) was heated for 5 h. Silica gel column chromatography (EtOAc) afforded 4.1.13.3. (1 4 S)-5 6 -hydroxy-4-oxa-1(4,1)-imidazolidina-3(1,4),5(1,3)-washed with 10% aqueous NaHSO3 solution, water and brine, then dried over Na2SO4 (s, 1H); 7.09 (d, J = 8.4 Hz, 2H); 6.91 (d, J = 8.2 Hz, 1H); 6.76 (d, J = 8.2 Hz, 2H); 6.74 column chromatography to provide the expected compound. +4 (c 0.5, MeOH). IR (neat) max : 1606 cm -1 . 1 H NMR (300 MHz, DMSO-d6)  7.25 and concentrated under reduced pressure. The crude residue was purified by silica gel pure compound 2e (17 mg, 71 % yield) as a colorless solid. Mp = 159-161 °C. D 20 = To a solution of the O-methylated derivative (1 equiv) in anhydrous CH2Cl2 at -78°C dibenzenacyclooctaphane-1 2 ,1 5 -dione(1d). Following the general procedure,
	4 Hz, (dd, J = 2.2 , 8.2 Hz, 1H); 4.80 (d, J = 2.0 Hz, 1H); 4.25-4.42 (m, 2H); 3.80 (s, 3H);

(EtOAc/PE = 3:7) provided triazole 15 (892 mg, 83.3%) as a colorless solid. Mp : 102°C. IR (neat) max : 1605 cm -1 .

1

H NMR (300 MHz, CD3CN)  7.30 (d, J = 2.0 Hz, 1H); 7.22 (s, 1H); 7.06-7.02 (m, 2H); 7.01 (dd, J = 2.0, 8.4 Hz, 1H); 6.90 (d, J = 8.

1

H NMR (300 MHz, DMSO-d6)  9.14 (s, 1H); 7.68 (s, 1H); 7.39 (d, J = 2.1 Hz, 1H); 7.07 (dd, J = 2.1, 8.4 Hz, 1H); 6.99-6.95 (m, 3H); 6.69-6.61 (m, 2H); 4.49 (t, J = 7.1 Hz, 2H); 3.80 (s, 3H); 3.05 (t, J = 7.1 Hz, 2H); 2.82-2.76 (m, 4H).

13

C NMR (75 chromatography (CH2Cl2/MeOH = 97:3) to provide the expected compound 2d (15 mg, 53% yield) as a yellow gum. D 20 = + 63.8 (c 1.0, CH2Cl2). IR (neat) max : 3300, 1756, 1696 cm -1 .

1

H NMR (300 MHz, MeOD)  7.37 (dd, J = 8.2, 2.2 Hz, 1H); 7.28 (dd, J = was added dropwise BBr3 (1M in hexane, 10 equiv). The reaction mixture was allowed to warm to 0°C, stirred for 1 to 4h, and then quenched with ice water. compound 2d (31 mg, 0.088 mmol) was stirred at 0°C for 1h. Silica gel column chromatography (CH2Cl2/MeOH = 97:3) afforded pure compound 1d (14 mg, 47% yield) as a colorless solid. Mp : 173-175°C. []D 20 = +35 (c 0.32, MeOH). IR (neat) max : 3262

Acknowledgments

The authors acknowledge the financial support from INSERM, CNRS, Université Paul Sabatier, the French "Ministère de l'Enseignement Supérieur et de la Recherche" 5grant to K.M.), and IdEx Emergence call-PALMA.

The authors wish to thank Nancy Geoffre and the GeT-TQ Platform (INSERM U1048, I2MC), and the Institut de Chimie de Toulouse (FR 3599) for their excellent technical assistance.

Appendix A. Supplementary data

Supplementary data related to this article can be found at

References and notes


Kelly Maurent

Corinne Vanucci-Bacqué

Nathalie Saffon-Merceron

Michel Baltas

Florence Bedos-Belval

Total Synthesis of Tedarene A

à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Natural and synthetic macrocycles have attracted growing attention in drug discovery and medicinal chemistry due to their favorable pharmacological properties. 1,2,3 Among them, the cyclic diarylheptanoids have been reported to mediate diverse remarkable biological activities including antioxidant, anti-inflammatory, antiviral and anticancer ones. 4,5,6 Diarylheptanoids are typical secondary metabolites widely distributed in plants that possess a 1,7diphenylheptane structural skeleton. Three subgroups can be distinguished i.e. linear diarylheptanoids from which the most known is curcumin, 7 cyclic biphenyl ([7,0]metacyclophanes) such as myricanone, 8 and cyclic diphenylethers that harbor a 14-oxa-[7,1]metaparacyclophane architecture with acerogenin A 9 or C 10 as examples (Figure 1). Among the cyclic diaryletherheptanoid (DAEH) family, tedarene A (Figure 1) was recently isolated 11 from the marine sponge Tedania ignis, commonly named the fire sponge. It is the first DAEH extracted from a marine organism. Tedarene A shows an inhibitory activity on nitric oxide production 11 that may have therapeutic utility to treat inflammatory pathologies. In view of its pharmacological activity, the total synthesis of tedarene A represents an attractive challenge for chemists as a way to provide sufficient amounts of pure product for further biological assays.

The unique structure of tedarene A comprises a 15-membered diaryl ether macrocycle displaying a phenol ring and an E,Z-conjugated diene unit in the seven-membered aliphatic chain. Herein, the first total synthesis of tedarene A is described. The key steps involve macrocyclization based on Ullmann coupling conditions and the regio-and stereoselective introduction of the two conjugated E,Z-alkene bonds by sequentially controlled reduction and elimination steps.

RESULTS AND DISCUSSION

As shown in the retrosynthetic analysis outlined in Scheme 1, we envisioned that tedarene A (1) could be obtained by a stereocontrolled dehydration of E-allylic alcohol 2 giving rise to the conjugated E,Z-diene moiety. The macrocyclic core of 2 could result from an intramolecular Ullmann condensation of the linear bromophenol 3. In turn, the E-double bond of 3 could stem from the controlled trans-hydrogenation of the propargyl alcohol 4. The latter could be readily accessed by condensation of the acetylide anion of alkyne 5 on the protected aldehyde 6.

Scheme 1. First Retrosynthetic Approach to Tedarene A (1)

Our synthesis of the propargyl compound 5 started with 3-bromo-4-methoxybenzaldehyde as shown in Scheme 2. Ethynylation by the acetylide anion of propargyltrimethylsilane provided alcohol 7 in 95% yield. Deoxygenation was readily achieved in 91% yield by treatment with catalytic heteropolyacid H3[PW12O40].nH2O in the presence of triethylsilane in dichloroethane. 12 It is of note that the trimethylsilyl alkyne 8a was obtained in mixture with the unexpected triethylsilyl analogue 8b (75/25 ratio) in 91% overall yield. This result was of no consequence on the synthesis as the next step consisted of a desilylation reaction. Initial treatment of a mixture of 8a and 8b with TBAF in THF at 0 °C led to allene 9 quantitatively.

Alternative treatment with K2CO3 in MeOH at 0 °C afforded a mixture of the expected compound 5 along with allene 9 and the starting triethylsilane 8b in a 60/20/20 ratio.

Fortunately, addition of acetic acid in the presence of TBAF allowed circumvention of the formation of allene 9. 13 After optimization of the reaction conditions (3 additions of the reactants TBAF and AcOH spread over 6 days), the expected alkyne 5 was obtained in 87 % yield.

Scheme 2. Synthesis of Alkene 5

The required aldehyde 6 (Scheme 3) was obtained starting with the demethylation of 4-(4methoxyphenyl)butanoic acid using hydrobromic acid in acetic acid at 150 °C to give rise to phenol 10 in 96% yield as previously described. [START_REF] Van Goor | Pyrazinecarboxamide derivatives as epithelial sodium channel inhibitors and their preparation, pharmaceutical compositions and use for the treatment of cystic fibrosis and other chronic diseases[END_REF] The regioselective protection of the phenol function as a t-butyldimethylsilyl ether was achieved by reaction with TBDMSCl in the presence of imidazole in DMF followed by treatment with K2CO3 in a MeOH/H2O mixture. 15 Acid 11 obtained in 78% yield was then reduced to alcohol 12 using LiAlH4 in 98% yield.

Subsequent oxidation with IBX finally gave aldehyde 6 in 62% yield.

Scheme 3. Synthesis of Aldehyde 6

With compounds 5 and 6 in hand, we next examined the addition of the acetylide anion of 5 on aldehyde 6. We first carried out the reaction in the presence of EtMgBr in THF. 16 No addition product was formed. The use of Carreira conditions (Zn(OTf)2, NEt3 in toluene) 17 equally failed to deliver the target compound. In both cases, starting materials were totally recovered. We next conducted the reaction using LDA as the base at -78 °C. 18 Attempts were made by varying the reaction temperature, reaction time and the order of addition of the reagents. Unfortunately, this reaction was found to be not reproducible with the formation of trace amounts of the expected compound along with various amounts of allene 9.

To overcome this failure due to the presence of acidic benzylic protons in alkyne 5, we turned our attention to an alternative strategy for the synthesis of tedarene A as depicted in Scheme 4.

The retrosynthetic strategy was still based on an intramolecular Ullmann cyclization. However, the timing of the formation of the double bonds was reversed. So, the E-alkene bond was envisonned to result from dehydration of the macrocyclic allylic alcohol 13 obtained by an Ullmann cyclization on bromophenol 14. The Z-double bond of 14 would arise from a stereocontrolled hydrogenation of the propargyl alcohol 15. The latter derivative was to be obtained more efficiently by condensing the acetylide anion of alkyne 17 onto aldehyde 16. This strategy overcomes the problems arising from the acidic benzylic protons of alkyne 5 under basic conditions and was expected to efficiently lead to the target tedarene A.

Scheme 4. Second Retrosynthetic Approach to Tedarene A (1)

Bromoaldehyde 16 was synthetized in two steps starting from 3-(4-methoxyphenyl)propan-1ol (Scheme 5). The regioselective monobromination of the aromatic ring by treating with bromine and aluminium chloride in CH2Cl2 and subsequent IBX oxidation of the resulting alcohol 18 led to the expected aldehyde 16 in 96% yield over two steps.

Scheme 5. Synthesis of Aldehyde 16

Alkyne 17 was readily obtained from the commercially available 4-hydroxybenzaldehyde via a known three-step sequence. 19 The acetylide anion of compound 17, efficiently formed by action of n-BuLi, was then condensed onto aldehyde 16 in THF to afford the expected propargyl alcohol 19 in 87% yield (Scheme 6). The controlled and stereospecific hydrogenation of the alkyne bond to a Z-double one was first envisioned by using 15% w/w Lindlar catalyst in the presence of 6% quinoline at 1 atm, in MeOH for 12 h. 20 Under these conditions, the starting material was fully recovered.

The expected transformation was then carried out under the same conditions without quinoline.

The observed conversion rate (evaluated by 1 H NMR) was 31%. Increasing the reaction time to 24 h enhanced the conversion rate to 50 %. However, the hydrogenation efficiency was not improved by increasing the reaction time up to 90 h or the catalyst amount up to 30% w/w.

Raising the hydrogen pressure to 3 atm for 24 h increased the conversion to 81%. Finally, optimized conditions (6 atm for 18 h) led to Z-alkene 20 in 99% isolated yield.

Cleavage of the TBS group of 20 was readily accomplished in 94% yield by treatment with TBAF in THF. Subsequent intramolecular Ullman cyclization on bromophenol 14 was achieved in the presence of CuO and K2CO3 in refluxing pyridine for 48 h. 21 Under these conditions, ring closure afforded macrocyclic compound 21 in good 70% yield. In order to reduce the reaction time, the cyclization was carried out under microwave heating. 22 The reaction was complete at 150 °C in 4 h and 21 was obtained in 81% an improved yield. The cyclic structure of 21 was confirmed by the typical shield shift of the H1 2 resonance (Scheme 6) shown in the 1 H NMR spectrum as a result of the anisotropic effect of the neighboring aromatic ring 21 (δH1 2 = 5.38 ppm in 21 vs. δH2 = 7.33 ppm in 14).

Scheme 6. Synthesis of the Macrocyclic Core of Tedarene A

At this point, the required E-alkene bond was expected to result from the stereospecific dehydration of the allylic alcohol 21. Treatment with mesyl chloride in the presence of NEt3 in CH2Cl2 from 0 °C to room temperature directly afforded 23 a 60/40 mixture of two diene derivatives (as estimated by 1 H NMR), in 75% overall yield. The use of preparative HPLC in direct phase conditions using a chiral phase column allowed the separation of the two isomers in respectively 44% and 13% isolated yields.

The 1 H and 13 C NMR spectra of the major isomer 22a appeared similar to those described for tedarene A along with some missing or hardly detectable signals at room temperature. The slow interconversion rate near the NMR time scale between the two enantiomeric conformations causes coalescence of some NMR signals at 25 °C. 24 The configurations of the double bonds, supposed to be identical to those of tedarene A i.e. 6Z,8E, was confirmed by single crystal Xray diffraction analysis of 22a (Figure 2). The NMR data of the minor isomer 22b are consistent with a 6E,8E configuration of the diene system with a rapid interconversion of the two enantiomeric conformations at room temperature. Regarding the coupling constant for alkenes protons, E (J = 14.7 Hz) and Z (J = 7.5 Hz) configurations are undoubted. Macrocycle 22b afforded needle crystals that were submitted to single crystal X-ray diffraction analysis (Figure 2). The resulting data confirmed the assigned configurations, which suggest a partial isomerization of the pre-established Z-double bond presumably via a carbocation intermediate. In order to complete the synthesis of tedarene A, the last O-demethylation step was then attempted using standard Lewis acid conditions as already described for diarylheptanoid derivatives. Unfortunately, the use of AlCl3 in refluxing CH2Cl2 26 or of BBr3 in CH2Cl2 at lower temperature (-78 °C27 to -40 °C28 ), led to the degradation of the starting material due to the high reactivity of the diene heptanoid moiety under these Lewis acid conditions.

Alternatively, the isomeric mixture 22a-b was treated in the presence of sodium thioethanolate in refluxing DMF 29 (Scheme 7). This procedure effectively allowed the expected Odemethylation. Beside a mixture of the expected phenols 1 and 23, a third isomer was detected, in a 26/32/42 ratio according to 1 H NMR. Flash chromatography allowed us to isolate the undesired compound 24 along with an inseparable mixture of 1 and 23. The spectroscopic data of 24 was in accordance with a 7E,9Z conjugated diene phenol structure, resulting from the deprotonation of the benzylic protons followed by the migration of the diene system under basic conditions.

Scheme 7. Demethylation of Macrocyles 22a-b

The formation of the unwanted derivative 24 prompted us to conduct the demethylation step earlier in the synthesis starting from the macrocyclic allylic alcohol 21 that does not contain any acidic benzylic protons (Scheme 8). When submitted to the previous demethylation conditions (EtSNa, DMF, reflux), macrocycle 21 cleanly afforded the expected phenol 13 in 79% yield.

Scheme 8. Synthesis of Tedarene A (1) and its Isomer 23

Treatment of phenolic allylic alcohol 13 with mesyl chloride in the presence of NEt3 from 0 °C to room temperature allowed the elimination reaction to proceed along with the unavoidable mesylation of the phenol leading to a mixture of diene E,Z and E,E-isomers 25a and 25b in 60/40 ratio (as determined by 1 H NMR), as previously observed for the mixture of 22a-b, in 80% overall yield. Hydrolysis of the mesylates was finally accomplished by action of aqueous sodium hydroxide 30 in an optimized 1:1 MeOH-dioxane mixture at 60 °C, in 67 % overall yield. This led to a mixture of isomers E,Z-1 and E,E-23 in the same ratio as the initial mixture and with no trace of double bond migration. A challenging preparative HPLC chromatography of this mixture due to the minor structure differences, using a chiral phase column in direct phase allowed the separation of the two macrocycles 1 and 23 in 38.5% and 23% respective isolated yields. The spectroscopic data of 1, in particular the 1 H and 13 C NMR spectra in CD3OD recorded at 25 °C and -40 °C, were in full agreement with those published for the naturally occurring tedarene A. 11 Moreover, both isomers crystallized from CH2Cl2 to give colorless crystals that were suitable for single crystal X-ray diffraction analysis (Figure 3). Their respective configurations was unambiguously confirmed by this analysis. In summary, we have completed the first total synthesis of the natural product tedarene A. The envisioned optimized strategy proceeded in nine steps and 15.3% overall yield from commercially available 3-(4-methoxyphenyl)propan-1-ol. The regio-and stereocontrol of the dienic system as well as the intramolecular Ullmann macrocylization represent the key features of this total synthesis. The previously unknown E,E-isomer of tedarene A was also prepared and fully characterized. This efficient synthesis provides convenient access to tedarene A for further biological assays and paves the way for the preparation of analogues for further SAR studies.

EXPERIMENTAL SECTION

General Experimental Procedures. Unless otherwise noted, all experiments were carried out under a nitrogen atmosphere. Solvents (CH2Cl2 and THF) were dried via a purification solvent system MB-SP-800 (MBRAUN). Melting points (mp) were obtained on a Buchi apparatus and are uncorrected. Measurements above 200°C were not possible with this apparatus. UV spectra were recorded in MeOH on a Hewlett Packard 8453 spectrometer at 25°C. IR spectra were recorded on a Thermo Nicolet Nexus spectrometer. NMR spectra were recorded on Brucker Avance 300 and 500 MHz spectrometers. The NMR spectra were acquired in CDCl3 and CD3OD, and the chemical shifts were reported in parts per million referring to CHCl3 (δH 7.26 for proton and δC 77.0 for carbon) and MeOH (δH 3.34 for proton and δC 49.0 for carbon), respectively. Signals are described as follow: s, singlet; brs, broad signal; d, doublet; t, triplet; m, multiplet. HRMS data were recorded on a Xevo G2 QTOF (Waters) instrument. Reactions were monitored by TLC on silica gel Alugram® Xtra SIL G/UV254. Column chromatography were performed on Machery-Nagel silica gel 0.063-0.2 mm. Flash chromatography purification was performed on Puriflash 430 (Interchim) equipped with a 30 m silica gel column PF-30SIHP-JP (Interchim). HPLC purification was performed using a system equipped with an UV detector. The column used was a ChiralPak IA for SFC (250×20 mm, 5 µm). Reactions utilizing microwave technology were conducted in a CEM Discover Benchmate microwave reactor (model no. 908010). (7). To a solution of propargyl trimethylsilane (854 L, 6.05 mmol) in dry THF (30 mL) at -78 °C under a N2 atmosphere was added dropwise n-BuLi (1.6 M in hexanes, 3.78 mL, 6.05 mml). The reaction mixture was stirred for 45 min and a solution of 3-bromo-4-methoxybenzaldehyde (1 g, 4.65 mmol) in THF

1-(3-Bromo-4-methoxyphenyl)-3-(trimethylsilyl)prop-2-yn-1-ol

(3-(3-Bromo-4-methoxyphenyl)prop-1-yn-1-yl)trimethylsilane (8a) and (3-(3-bromo-4methoxyphenyl)prop-1-yn-1-yl)triethylsilane (8b).

To solution of propargyl alcohol 7 (1.2 g, 3.85 mmol) in 1,2-dichloroethane (12 mL) was added H3PW12O4.nH2O (111 mg, 3.95 10 -2 mmol) then Et3SiH (0.92 mL, 5.77 mmol). The reaction mixture was heated at 50 °C for 2 h.

After cooling to room temperature, the mixture was quenched with satd aq NaHCO3 solution.

The aqueous layer was extracted CH2Cl2. The combined organic layers were washed with satd aq NaHCO3 solution, H2O, brine, dried over Na2SO4, and concentrated under reduced pressure.

The crude residue was purified by column chromatography on silica gel (EtOAc/PE = 3:97) to provide an inseparable (73/27) mixture of trimethyl and triethylsilyl compounds 8a and 8b (0.95 g, 91%) as colorless oil. Rf = 0.65 (EtOAc/PE = 2:8); IR (neat) 2176 cm -1 ; For 8a (From a mixture) 1 H NMR (CDCl3, 300 MHz) δ 7.51 (d, 1H, J = 2.2 Hz), 7.24 (dd, 1H, J = 8.4, 2.2 Hz), 6.85 (d, 1H, J = 8.4 Hz), 3.88 (s, 3H), 3.57 (s, 2H), 0.19 (s, 9H); 13 C NMR (CDCl3, 75 MHz) δ. 154.7, 132.8, 130.0, 127.9, 112.0, 111.7, 104.0, 87.4, 56.4, 25.0, 0.17; For 8b (From a mixture) 1 H NMR (CDCl3, 300 MHz) δ 7.55 (d, 1H, J = 2.2 Hz), 7.24 (dd, 1H, J = 8.4, 2.2 Hz), 6.85 (d, 1H, J = 8.4 Hz), 3.88 (s, 3H), 3.60 (s, 2H), 1.01 (t, 9H, J = 7.8 Hz), 0.62 (qd, 6H, J = 7.8, 0.8 Hz) ; 13 C NMR (CDCl3, 75 MHz) δ 154.6, 132.8, 130.2, 127.8, 111.9, 111.6, 104.9, 84.8, 56.4, 25.1, 7.6, 4.6. (9). A 73/27 mixture of derivatives 8a-8b (232 mg, 0.78 mmol) was dissolved in dry THF (10 mL) and cooled to 0 °C. A TBAF solution (1M in THF, 1.56 mL, 1.56 mmol) was added dropwise. The reaction mixture, which turned red immediately, was warmed to rt and stirred for 1 h. Water was added and the aqueous layer was extracted with EtOAc. The combined organic layers were washed with H2O, brine and dried over Na2SO4. Concentration under reduced pressure provided allene 9 (171 mg, 97%) as a yellow oil which was pure enough for use without further purification. Rf = 0.32 (EtOAc/PE = 5:95); IR (neat) 1941cm -1 ; 1 H NMR (CDCl3, 300 MHz) δ 7.49 (d, 1H, J = 2.1 Hz), 7.17 (dd, 1H, J = 8.4, 2.1 Hz), 6.84 (d, 1H, J = 8.4 Hz), 6.06 (t, 1H, J = 6.8 Hz), 5.16 (d, 2H, J = 6.8 Hz), 3.88 (s, 3H); 13

2-Bromo-1-methoxy-4-(propa-1,2-dienyl)benzene

2-Bromo-1-methoxy-4-(prop-2-ynyl)benzene (5).

A 73/27 mixture of derivatives 8a-8b (1.26 g, 4.07 mmol) was dissolved in dry THF (40 mL) and cooled to 0 °C. AcOH (1.16 mL, 20 mmol) and TBAF solution (1M in THF, 16.3 mL, 16.3 mmol) were added dropwise and the reaction mixture was allowed to warm to rt. Two supplementary additions of AcOH (0.7 mL, 12.2 mmol) and TBAF solution (8.15 mL, 8.15 mmol) were realized after stirring for 48 h and 96 h. After 6 days of reaction time at rt, H2O was added and the aqueous layer was extracted with EtOAc. The combined organic layers were washed with satd aq NaHCO3 solution, H2O, brine, dried over Na2SO4, and concentrated under reduced pressure. The crude residue was purified by column chromatography on silica gel (EtOAc/PE = 5:95) to provide alkyne 5 (772 mg, 87%) as a yellow oil. Rf = 0.38 (EtOAc/PE = 1:9); IR (neat) 3271cm -1 ; 1 H NMR (CDCl3, 300 MHz) δ 7.54 (d, 1H, J = 1.9 Hz), 7.24 (dd, 1H, J = 8.4, 1.9 Hz), 6.85 (d, 1H, J =8.4 Hz), 3.88 (s, 3H), 3.53 (d, 2H, J = 2.75 Hz), 2.20 (t, 1H, J = 2.75 Hz); 13 (11). To an ice cooled solution of acid 10 (100 mg, 0.55 mmol) in dry DMF (5 mL) under N2 were added imidazole (227 mg, 3.33 mmol) and TBDMSCl (251 mg, 1.66 mmol). The reaction mixture was stirred at 0 °C for 1 h and allowed to warm to rt. The reaction was quenched with aq 1M KHSO4 solution. The aqueous layer was extracted with EtOAc and the combined organic layers were washed with 1M KHSO4 solution, satd aq NaHCO3 solution, H2O and brine, dried over Na2SO4 and concentrated under reduced pressure. K2CO3 (115 mg, 0.83 mmol) in H2O (1.5 mL) was added to a solution of the obtained crude disilylate in THF (3 mL) and MeOH (1.5 mL). The mixture was stirred at rt for 12 h. After dilution with EtOAc, the organic layer was extracted with satd aq Na2CO3 solution. The aqueous layer was extracted with EtOAc, acidified with conc HCl solution to pH = 1, and re-extracted with EtOAc. The combined organic layers were washed with H2O, brine, dried over Na2SO4 and concentrated under reduced pressure to yield acid 11 (128 mg, 78%) pure enough to be used without further purification. The physical data and NMR spectra were in agreement with the literature. 31 (12). To a suspension of LiAlH4 (33 mg, 0.87 mmol) in dry THF (5 mL) at 0 °C under N2 was added dropwise a solution of aldehyde 11 (128 mg, 0.43 mmol) in THF (5 mL). The reaction mixture was allowed to warm to rt and quenched with aq 3M HCl solution. The aqueous layer was extracted with EtOAc and the combined organic layers were washed with satd aq NaHCO3 solution, brine, dried over Na2SO4, and concentrated under reduced pressure. Alcohol 12 (119 mg, 98%) was obtained as yellow oil with no further purification. The physical data and NMR spectra were in agreement with the literature. 31 (6). To a solution of alcohol 12 (1.27 g, 4.53 mmol) in EtOAc (30 mL) was added IBX (2.54 g, 9 mmol). The reaction mixture was refluxing for 3 h then cooled to rt and filtered over a Celite pad. The filtrate was concentrated under reduced pressure. The crude residue was purified by column chromatography (EtOAc/PE = 1:9) to provide aldehyde 6 (787mg, 62%) as a colorless oil. The physical data and NMR spectra were in agreement with the literature. [START_REF] Englung | Synthetic Progress Toward Parvis temonine, Spiroxins A and B, and Generation of Palmarumycin Analogues[END_REF] (18). To a solution of 3-(4-methoxyphenyl) propan-1-ol (4.4 g, 26.47 mmol) in CH2Cl2 (100 mL) were added AlCl3 (3.53 g, 26.47 mmol) and Br2

4-(4-((tert-Butyldimethylsilyl)oxy)phenyl)butanoic acid

4-(4-((tert-Butyldimethylsilyl)oxy)phenyl)butan-1-ol

4-(4-((tert-Butyldimethylsilyl)oxy)phenyl)butanal

3-(3-Bromo-4-methoxyphenyl)propan-1-ol

(1.35 mL, 26.47 mmol) dropwise at 0 °C under N2. The reaction was allowed to stir at 0 °C for 30 min and was quenched with ice water. The aqueous layer was extracted with CH2Cl2. The combined organic layers were washed with H2O, satd aq NaHCO3 solution, brine, dried over Na2SO4, and concentrated under reduced pressure. Alcohol 18 (6.45 g, 99%) was obtained as a colorless oil with no further purification. Rf= 0.23 (EtOAc/EP = 2:3). IR (neat) νmax 3300 cm -1 .

1 H NMR (CDCl3, 300 MHz) δ 7.39 (d, 1H, J = 2.1 Hz), 7.09 (dd, 1H, J = 8.4, 2.1 Hz), 6.82 (d, 1H, J = 8.1 Hz), 3.87 (s, 3H), 3.66 (t, 2H, J = 6.3 Hz), 2.64 (t, 2H, J = 7.5 Hz), 1.90-1.81 (m, 2H). 13 C NMR (CDCl3, 75 MHz) δ 154. 2, 135.6, 133.3, 128.4, 112.1, 111.6, 62.1, 56.4, 34.3, 30.9. HRMS (DCI, CH4): m/z 245.0177 [M+H] + (calcd for C10H14BrO2, 245.0162). (16). To a solution of alcohol 18 (2 g, 8.16 mmol) in EtOAc (75 mL) was added IBX (8 g, 28.57 mmol). The reaction mixture was refluxing for 3h then cooled to rt and filtered over a Celite pad. The filtrate was concentrated under reduced pressure to provide aldehyde 16 (1.92 g, 97 %) as colorless oil pure enough to be used without further purification. Rf = 0.37 (EtOAc/PE = 3:7) ; IR (neat) νmax 1720 cm -1 ; 1 H NMR (CDCl3, 300 MHz) δ 9.80 (t, 1H, J = 1.2 Hz), 7.37 (d, 1H, J = 2.1 Hz), 7.09 (dd, 1H, J = 2.4, 8.4 Hz), 6.82 (d, 1H, J = 8.4 Hz), 3.86 (s, 3H), 2.90-2.85 (m, 2H), 2.78-2.72 (m, 2H); 13

3-(3-Bromo-4-methoxyphenyl)propanal

1-(3-Bromo-4-methoxyphenyl)-7-(4-(tert-butyldimethylsilyloxy)phenyl)hept-4-yn-3-ol (19).

To a stirred solution of alkyne 17 (0.385 g, 1.48 mmol) in dried THF (15 mL) at -78 °C under N2 was added dropwise n-BuLi (1.6 M in hexane, 1.11 mL, 1.78 mmol). After stirring for 45 min at -78 °C a solution of aldehyde 16 (0.359 g, 1.48 mmol) in dry THF (5 mL) was added. The resulting mixture was allowed to warm up to rt and was stirred for another 90 min, then quenched with satd aq NH4Cl solution and the aqueous layer was extracted with Et2O. The combined organic layers were washed with satd aq NH4Cl solution, H2O and brine then dried over Na2SO4 and then concentrated under reduced pressure. The crude residue was purified by column chromatography on silica gel (EtOAc/PE = 1:9) to provide propargyl alcohol 19 (0.65 g, 87 %) as a light yellow oil. Rf = 0.38 (EtOAc/PE = 3:7); IR (neat) νmax 3390, 1500, 1260 cm - 1 ; 1 H NMR (CDCl3, 300 MHz) δ 7.38 (d, 1H, J = 2.1 Hz), 7.07 (dd, 1H, J = 8.4, 2.1 Hz), 7.07 (d, 2H, J = 8.7 Hz), 6.54 (d, 1H, J = 8.4 Hz), 6.76 (d, 2H, J = 8.7 Hz), 4.31 (tt, 1H, J = 6.3, 1.9 Hz), 3.87 (s, 3H), 2.76 (t, 2H, J = 7.5 Hz), 2.66 (t, 2H, J = 7.8 Hz), 2.48 (td, 2H, J = 7.5, 1.9 Hz), 1.98-1.87 (m, 2H), 0.97 (s, 9H), 0.17 (s, 6H) ; 13

(4Z)-(3-Bromo-4-methoxyphenyl)-7-(4-(tert-butyldimethylsilyloxy)phenyl)hept-4-en-3-ol (20).

To a solution of alkyne 19 (52 mg, 0.1 mmol) in EtOH (3.3 mL) was added Lindlar catalyst (7.8 mg, 15% w/w) and the reaction mixture was subjected to 6 atm of hydrogen at rt for 18h.

Filtration over a Celite pad and concentration under vacuum yield alkene 20 (53 mg, 99%) as a light yellow oil pure enough to be used in the next step without further purification. Rf = 0.32 (EtOAc/PE = 2:8); IR (neat) νmax 3360, 1610 cm -1 ; 1 H NMR (CDCl3, 300 MHz) δ 7.35 (d, 1H, J = 2.1 Hz), 7.05 (dd, 1H, J = 8.1, 2.1 Hz), 6.99 (d, 2H, J = 8.7 Hz), 6.80 (d, 1H, 8.1 Hz), 6.76 (d, 2H, J = 8.7 Hz), 5.52 (dtd, 1H, J = 10.8, 7.8, 0.9 Hz), 5.39 (ddt, 1H, J = 10.8, 8.4, 1.2 Hz), 4.22 (dt, 1H, J = 8.4, 6.6 Hz), 3.87 (s, 3H), 2.69-2.45 (m, 4H), 2.41-2.25 (m, 2H), 1.79 (dtd, 1H, J = 13.5, 6.9, 8.4 Hz), 1.58 (dtd, 1H, J = 13.5, 6.9, 9.3 Hz), 0.97 (s, 9H), 0.18 (s, 6H); 13 (Z)-4-(7-(3-Bromo-4-methoxyphenyl)-5-hydroxyhept-3-enyl)phenol (14). To a solution of silylether 20 (0.698 g, 1.38 mmol) in dry THF (15 mL) was added dropwise TBAF (1M solution in THF, 2.76 mmol). After stirring for 30 min at 0 °C, the reaction mixture was quenched with sat aq NaHCO3 (5 mL), and the aqueous layer was extracted with Et2O. The combined organic layers were washed with satd aq NaHCO3, H2O and brine, then dried over Na2SO4 and concentrated under reduced pressure. The crude residue was purified by column chromatography on silica gel (1% MeOH in CH2Cl2) to provide aldehyde 14 (0.51g, 94%) as a colorless gum. Rf = 0.22 (1% MeOH in CH2Cl2) ; IR (neat) νmax 3315, 1610, 1510 cm -1 ; 1 H NMR (CDCl3, 300 MHz) δ 7.33 (d, 1H, J = 2.1 Hz), 7.04 (dd, 1H, J = 8.4, 2.1 Hz), 7.00 (d, 2H, J = 8.7 Hz), 6.80 (d, 1H, J = 8.4 Hz), 6.75 (d, 2H, J = 8.7 Hz), 5.53 (dt, 1H, J = 10.9, 7.7 Hz), 5.40 (dd, 1H, J = 10.9, 9 Hz), 4.17 (dt, 1H, J = 8.7, 7.2 Hz), 3.87 (s, 3H), 2.71-2.47 (m, 4H), 2.36-2.28 (m, 2H), 1.76 (dtd, 1H, J = 13.4, 8.6, 6.9 Hz), 1.53 (ddt, 1H, J = 13.4, 9.4, 6.9 Hz); 13 (Z)-1 6 -Methoxy-2-oxa-1(1,3),3 (1,4)-dibenzenacyclodecaphan-6-en-8-ol (21).

By conventional heating: To a solution of phenol 20 (406 mg; 1.04 mmol) in anhydrous pyridine (53 mL) was added K2CO3 (287 mg; 2.08 mmol). The mixture was warmed to 90 °C and CuO (207 mg; 2.6 mmol) was added. After heating was for 48 h, the reaction mixture was cooled to rt and concentrated under reduced pressure. The residue was dissolved in EtOAc and neutralized by addition of 10% aq NaHSO3 solution. The aqueous layer was extracted with EtOAc and the combined organic layers were washed with 10% aq NaHSO3 solution, water and brine, then dried over Na2SO4 and concentrated under reduced pressure. The crude residue was purified by column chromatography on silica gel (EtOAc/pentane = 3:7) to provide compound 21 (226 mg, 70%) as a gum.

By microwave heating: A mixture of 20 (31 mg, 7.92 10 -5 mol), K2CO3 (22 mg, 1.58 10 -4 mol) and CuO (16 mg, 1.98 10 -4 mol) in pyridine (4 mL) was heated at 150°C under microwave irradiation in a sealed tube for 4 h. The reaction mixture was treated as described above to yield, after column chromatography, the expected compound 21 (20 mg, 81%). Rf = 0.21 (EtOAc/PE = 3:7); IR (neat) νmax 3400, 1590, 1520, 1500, 1220 cm -1 ; RMN

ASSOCIATED CONTENTS Supporting Information

The Supporting Information is available free of charge on the ACS Publications website at DOI:

Table of Contents/Abstract Graphic

Figure 1 .

 1 Figure 1. Representative diarylheptanoid natural products.

Figure 2 .

 2 Figure 2. X-ray crystal structure of 22a and 22b. Thermal ellipsoids represent 30% probability level. For clarity, disordered atoms and H atoms are omitted except the dienic and phenolic ones. 25

Figure 3 .

 3 Figure 3. X-ray structures of 1 and 23. Thermal ellipsoids represent 30% probability level. The asymmetric unit contains two independent molecules, only one is shown here. For clarity, disordered atoms and H atoms are omitted except the diene and phenolic ones. 25

(

  10 mL) was added dropwise. The reaction was allowed to warm to 0 °C and quenched with satd aq NH4Cl solution. The aqueous layer was extracted with EtOAc. The combined organic layers were washed with satd aq NH4Cl solution, H2O, brine, dried over Na2SO4, and concentrated under reduced pressure. The crude residue was purified by column chromatography on silica gel (EtOAc/PE = 1:9) to provide propargyl alcohol 7 (1.39 g, 95%) as a light yellow oil. Rf = 0.41 (EtOAc/PE = 2:8); IR (neat) 3370, 2173 cm -1 ; 1 H NMR (CDCl3, 300 MHz) δ 7.73 (d, 1H, J = 1.8 Hz), 7.44 (dd, 1H, J = 8.4, 1.8 Hz), 6.89 (d, 1H, J = 8.4 Hz), 5.38 (d, 1H, J = 6 Hz), 3.90 (s, 3H), 2.23 (d, 1H, J = 6 Hz), 0.21 (s, 9H); 13 C NMR (CDCl3, 75 MHz) δ 155.9, 134.1, 132.0, 127.1, 111.8, 111.7, 104.7, 92.0, 63.9, 56.4, -0.1; HRMS (ESI) : m/z 295.0150 [M+H-H2O] + (calcd for C13H16BrOSi, 295.0154).

  C NMR (CDCl3, 75 MHz) δ 201.3, 154.5, 134.1, 133.1, 128.4, 112.1, 111.7, 56.4, 45.3, 26.9; HRMS (DCI, CH4) : m/z 243.0022 [M+H] + (calcd for C10H12BrO2, 243.0021).

  C NMR (CDCl3, 75 MHz) δ 154.3, 154.2, 135.3 (2C), 133.4, 129.4, 128.5, 120.0, 112.1, 111.6, 85.6, 81.7, 61.9, 56.4, 39.6, 34.3, 30.3, 25.8, 21.2, 18.3, -4.3. HRMS (DCI, CH4,): m/z 501.1442 [M-H] + (calcd for C26H34BrO3Si, 501.1461).

  1 H (CDCl3, 300 MHz) δ 7.31 (dd, 1H, J = 8.1, 2.1 Hz), 7.07-6.98 (m, 3H),6.77 (d, 1H, J = 8.4 Hz), 6.62 (dd, 1H, J = 8.1, 2.1 Hz), 5.53 (dddd, 1H, J = 11.1, 10.8, 4.8, 0.9 Hz), 5.43 (ddd, 1H, J = 10.8, 7.1, 0.9 Hz), 5.38 (d, 1H, J = 2.1 Hz), 3.94 (s, 3H), 3.59 (ddd, 1H, J = 9.9, 7.2, 2.7 Hz), 3.04 (ddd, 1H, J = 12.9, 5.7, 2.1 Hz.), 2.67 (dd, 1H, J = 16.2, 9.3 Hz), 2.71-2.50 (m, 4H), 1.74 (dddd, 1H, J = 14.7, 8.7, 10.2, 1.8 Hz), 1.49-1.25 (m, 1H); RMN 13 C (CDCl3, 75 MHz) δ 155.8, 151.7, 146.3, 139.8, 135.3, 134.0, 133.3, 130.7, 130.6, 124.6, 123.2, 121.2, 115.7, 111.7, 66.4, 56.3, 38.7, 34.7, 32.9, 27.7; HRMS (DCI, CH4) m/z 310.1569 [M] + (calcd for C20H22O3, 310.1561). (42 mg, 1.18 10 -4 mol) in dioxane (3.5 mL) were added successively MeOH (3.5 mL)and aq 20% NaOH solution (9 mL). The reaction mixture was stirred at 60 °C for 3 h then cooled to 0 °C. Aqueous 3M HCl solution was added and the aqueous layer was extracted with CH2Cl2. The combined organic layers were washed with aq 3M HCl solution, H2O and brine, dried over Na2SO4 and concentrated under vacuum. Column chromatography on silica gel (CH2Cl2) of the residue yielded a 60/40 mixture of isomers 1 and 23 (22 mg, 67%). Preparative HPLC (Eluent: heptane /iPrOH = 99:1; Flowrate: 20 mL/min) allowed isolation of pure isomer 1 (12.7 mg, 38.5 %) and 23 (7.6 mg, 23%) as colorless solids. Rf = 0.23 (CH2Cl2/pentane = 1:1). For 23 : colorless block crystals (CH2Cl2); mp 156-157 °C; UV (MeOH) max (log ) 271 (3.60) nm, 241 (4.42) nm; IR (neat) νmax 3512, 1593 cm -1 ; 1 H NMR (CD3OD, 300 MHz) δ 7.13 (d, 2H, J = 8.4 Hz), 6.92 (d, 2H, J = 8.4 Hz), 6.70 (d, 1H, J = 8.0 Hz), 6.57 (dd, 1H, J = 8.0, 2.1 Hz), 5.70 (d, 1H, J = 2.1 Hz), 5.66-5.57 (m, 2H), 5.20-5.10 (m, 2H), 3.05 (d, 2H, J = 7.5 Hz),2.91 (t, 2H, J = 6.8 Hz), 2.46 (q, 2H, J = 7 Hz);13 C NMR (CD3OD, 125 MHz) δ 155.2, 150.6, 144.6, 140.1, 134.8, 134.2, 133.0, 132.0, 131.6, 131.0, 124.3, 122.1, 117.5, 116.6, 37.0, 35.0, 34.7; HRMS (DCI, CH4) : m/z 279.1396 [M+H] + (calcd for C19H19O2, 279.1385).For tedarene A 11 (1): colorless block crystals (CH2Cl2); mp 122˗123 °C; IR (neat) νmax 3451, 1605 cm -1 ; 1 H NMR (CD3OD, 300 MHz, 25 °C) δ 7.34-6.83 (broad coalescent signals, 4H), 6.65 (d, 1H, J = 7.9 Hz), 6.50 (dd, 1H, J = 7.9, 2.1 Hz), 5.94 (dd, 1H, J = 11.4, 10.4 Hz), 5.72 (dd, 1H, J = 15.1, 11.1 Hz), 5.45 (dt, 1H, J = 15.6, 7.6 Hz), 5.42 (d, 1H, J = 2.1 Hz), 5.31 (dt, 1H, J = 11.0, 8.3 Hz), 2.94 (d, 2H, J = 7.9 Hz), 2.40 (brs, 2H) ; 1 H NMR (CD3OD, 300 MHz, ˗ 40°C) δ 7.38 (dd, 1H, J = 8.3, 2.2 Hz), 7.04 (dd, 1H, J = 8.0, 2.1 Hz), 7.03 (dd, 1H, J = 8.2, 2.1 Hz), 6.79 (dd, 1H, J = 8.2, 2.4 Hz), 6.63 (d, 1H, J = 7.8 Hz), 6.52 (dd, 1H, J = 7.9, 2.1 Hz), 5.95 (t, 1H, J = 11.0 Hz), 5.72 (dd, 1H, J = 15.0, 10.9 Hz), 5.47 (m, 1H), 5.40-5.28 (m, 1H), 5.35 (d, 1H, J = 2 Hz),3.08-2.99 (m, 1H), 2.97-2.91 (m, 2H), 2.51 (td, 1H, J = 12.0, 2.5 Hz), 2e".45-2.35 (m, 2H) ; 13 C NMR (CD3OD, 75 MHz, 25°C) δ (four C not detectable because of a coalescence at rt) 156.6, 151.7, 144.5, 140.9, 133.8, 131.8, 131.6, 129.6, 129.2, 121.6, 118.0, 116.4, 36.9, 36.0, 33.0; 13 C NMR (CD3OD, 75 MHz, ˗ 40°C) δ 156.2, 151.5, 144.4, 141.0, 133.8, 133.3, 131.7, 131.5, 131.2, 129.6, 129.3, 125.5, 123.7, 121.6, 117.6, 116.0, 36.9, 35.9, 33.0; HRMS (DCI, CH4) : m/z 278.1298 [M] + (calcd for C19H18O2, 278.1307).

	(6Z,8E)-1 6 -Methoxy-2-oxa-1(1,3),3(1,4)-dibenzenacyclodecaphane-6,8-diene	(22a)	and
	(6E,8E)-1 6 -Methoxy-2-oxa-1(1,3),3(1,4)-dibenzenacyclodecaphane-6,8-diene (22b). To a
	solution of alcohol 21 (227 mg; 0,731 mmol) in CH2Cl2 (10 mL) at 0 °C were added dropwise
	NEt3 (306 L, 2.19 mmol) and CH3SO2Cl (68 L, 0.878 mmol). After stirring at 0 °C for 90
	min and at rt for 3 h, the reaction mixture was quenched with satd aq NH4Cl solution. The
	aqueous layer was extracted with CH2Cl2. The combined organic layers were washed with satd
	aq NH4Cl solution, H2O and brine then dried over Na2SO4 and concentrated under vacuum.
	Column chromatography on silica gel (CH2Cl2/pentane = 3/7) of the residue to yielded a 60/40
	mixture of isomers 22a and 22b (161 mg, 75%). Preparative HPLC (Eluent: heptane /CH2Cl2
	= 95/5. Flowrate: 15 mL/min) allowed isolation of pure isomer 22a (94 mg, 44%) and 22b (38
	mg, 13%) as colorless crystals. Rf = 0.31 (CH2Cl2/pentane = 2:8). For 22a : colorless block
	(CH2Cl2); mp > 200°C; UV (MeOH) max (log ) 277 (3.26) nm, 247 (3.98) nm; IR (neat) νmax
	2960 cm -1 ; 1 H NMR (CDCl3, 300 MHz, 25 °C) δ 7.23-6.88 (broad coalescent signals, 4H),
	6.75 (d, 1H, J = 8.1 Hz), 6.64 (dd, 1H, J = 8.1, 2.1 Hz), 5.97 (dd, 1H, J = 11.1, 10.8 Hz), 5.71

(ddd, 1H, J = 15, 10.8, 0.6 Hz), 5.53 (dt, 1H, J = 15.3, 7.8 Hz), 5.45 (d, 1H, J = 2.4 Hz), 5.31 (dt, 1H, J = 11.1, 8.6 Hz), 3.94 (s, 3H), 3.01 (d, 2H, J = 7.8 Hz), 2.40 (brs, 2H) ; 13 C NMR of 25a-b

1 H and 13 C NMR spectra of all new compounds. 1 H spectra of known compounds, X-ray crystallographic data of 1, 22a, 22b and 23 (PDF). X-ray data for 1 (CIF).

X-ray data for 22a (CIF).

X-ray data for 22b (CIF).

X-ray data for 23 (CIF).

ACKNOWLEDGMENTS

We thank the French 'Ministère de l'Enseignement Supérieur et de la Recherche' (grant to K.M.). Thanks are also due to the CNRS and the "Université Paul Sabatier" for financial support.

AUTHOR INFORMATION

Corresponding Author *E-mail: bedos@chimie.ups-tlse.fr

Notes

The authors declare no competing financial interest.