Celebratory Symposium A – Catalysis and the Periodic Table From a 175 year old Ruthenium to its Empire on Green Catalysis and Sustainable Chemistry

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One pot Pd(OAc)2-catalysed 2,5-diarylation of imidazoles derivatives

International audienceThe regioselective 2- or 5-arylation of imidazole derivatives with aryl halides using palladium catalysts has been described in recent years; whereas the arylation at both C2 and C5 carbons of imidazoles in high yields has not been performed. We found conditions allowing the access to these 2,5-diarylimidazoles via a one pot reaction. The choice of the base was found to be crucial to obtain these products in high yields. Using CsOAc as the base, DMA as the solvent and only 2 mol % of the phosphine-free Pd(OAc)2 the catalyst, the target 2,5-diarylated imidazoles were obtained in moderate to good yields with a wide variety of aryl bromides. Substituents such as fluoro, trifluoromethyl, formyl, acetyl, propionyl, ester, nitro or nitrile on the aryl bromide were tolerated. Sterically congested aryl bromides or heteroaryl bromides can also be employed. Surprisingly the nature of the substituent at position 1 on the imidazole derivative exhibits a huge influence on the reaction

Synthesis of a square-planar rhodium alkylidene N-heterocyclic carbene complex and its reactivity toward alkenes

The first rhodium alkylidene square-planar complex stabilized by an N-heterocyclic carbene ligand, RhCl(-CHPh)(IPr)PPh3 (2; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-carbene), has been prepared by reaction of RhCl(IPr)(PPh3)2 (1) with phenyldiazomethane and its dynamic behavior in solution studied. Treatment of 2 with alkenes results in the formation of the ¿2-olefin complexes RhCl(¿2-CH2-CHR)(IPr)PPh3 (3, R = H; 4, R = Ph; 5, R = OEt) and new olefins arising from the coupling of the alkylidene with the alkenes, likely via a metallacyclobutane intermediate

Green chemistry and sustainable development

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ISOM XVII, Pasadena

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International conference on organometallic and coordination chemistry

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Indo-French workshop

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Frontiers in Homogeneous Catalysis

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Nacional encuentro de quimica inorganica

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Ruthenium(II)-catalysed functionalisation of C-H bonds with alkenes: Alkenylation versus alkylation

International audienceThis chapter describes the recent achievements since 2011 of ruthenium(II)-catalysed transformations of sp2C-H bonds of a variety of functional arenes, heterocycles, alkenes and ferrocene derivatives on their reaction with alkenes, either via oxidative dehydrogenation to produce functional alkenes or via formal insertion of alkene into C-H bonds to afford alkylated products. The regioselectivity of ortho C-H bond alkenylation or alkylation is shown to be directed by both strongly and weakly coordinating functional groups from N-heterocycles and bidentate groups to carbonylcontaining groups such as ketone, ester, amide, carbamate and sulfonic acid derivatives. The ruthenium(II) catalysts often based on [RuCl2(p-cymene)]2 or RuCl2(PPh3)3 derivatives sometimes require the presence of a halide abstractor and an oxidant. The alkenylation of heterocycles will be shown to occur in the presence of base and their alkylation in the presence of proton source to give branched or linear alkylated isomers. Discussion of catalytic mechanism will involve the initial formation of a cyclometallate via C-H bond deprotonation and that of an intermediate resulting from alkene insertion into the Ru-C bond before its evolution to alkenylation or alkylation. © Springer International Publishing Switzerland 2015