Catalytic three-phase diastereoselective hydrogenation of o-toluic and 2-methyl nicotinic acid derivatives: in-situ FTIR/ATR investigation

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Catalytic three-phase diastereoselective hydrogenation of o-toluic and 2-methyl nicotinic acid derivatives: In situ FTIR/ATR investigation

International audienceCatalytic diastereoselective hydrogenation of o-toluic and 2-methyl nicotinic acids covalently bound to various chiral auxiliaries was carried out in a three-phase slurry reactor and followed in real time by means of in situ Fourier transform infrared/attenuated total reflection (FTIR/ATR) spectroscopy. The measurements show that the catalytic hydrogenation of o-toluic acid derivatives undergoes direct transformation to corresponding cyclohexanoic compounds. On the contrary, the presence of the nitrogen atom in the nicotinyl ring affects deeply the mechanism of hydrogenation by favoring the accumulation of tetrahydropyridine intermediate in the liquid phase, which is probably caused by modifying the adsorption mode on the metallic surface. It was demonstrated that data provided by examining corresponding IR stack plots by employing a chemometric, self-modeling curve resolution algorithm are more reliable than data derived from off-line GC analysis

Cross-metathesis with acrylonitrile and applications to fatty acid derivatives

International audienceIn this minireview, we report on the state of the art concerning the cross-metathesis of acrylonitrile with olefins. A special focus is given to catalytic conditions that are suitable for medium-size and long-chain aliphatic model substrates. The recent applications of this metathesis reaction to fatty acid derivatives to generate fatty nitriles and bifunctional products are considered. They represent very attractive transformations for the access to N-containing monomers and functional intermediates for the chemical industry from renewable raw materials

Ruthenium-alkylidene catalysed cross-metathesis of fatty acid derivatives with acrylonitrile and methyl acrylate: a key step toward long-chain bifunctional and amino acid compounds

International audienceThe ruthenium catalysed cross-metathesis of fatty-esters arising from plant oils with acrylonitrile is presented. The resulting linear nitrile ester products have potential as new intermediates for polyamides synthesis. A series of commercially available catalysts are able to promote the transformation of methyl 10-undecenoate 1, dimethyl octadec-9-en-1,18-dioate 5 and methyl ricinoleate 9 with acrylonitrile and a protocol based on the slow addition of catalyst allowed TONs as high as 1900 (92% yield) to be reached for cross-metathesis with acrylonitrile. These cross-metathesis conditions have been applied to methyl acrylate and TONs up to 7600 were obtained

Renewable materials as precursors of linear nitrile-acid derivatives via cross-metathesis of fatty esters and acids with acrylonitrile and fumaronitrile

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Phosphasalen group IV metal complexes: synthesis, characterization and ring opening polymerization of lactide

We report the synthesis of a series of Zr and Ti complexes bearing phosphasalen which differs from salen by the incorporation of two P atoms in the ligand backbone. The reaction of phosphasalen proligands(1a-1c)H2with Zr(CH2Ph)4led to different products depending on the nature of the N,N-linker in the ligand. In the case of ethylene-linked phosphasalen, octahedral Zr complex2aformed as a single stereoisomer intransgeometry. With the phenylene linker, it was shown by dynamic NMR spectroscopy that complex2bexists as a mixture oftransandcis-ß isomers in solution, both enantiomers (? and ?) of thecis-ß isomer being in fast equilibrium with respect to the NMR time-scale. The use of a propylene-linked phosphasalen proligand1cH2led to a mixture of complexes among which a binuclear Zr complex2cbridged only by one phosphasalen ligand could be isolated and characterized. Addition of 2 equiv. ofiPrOH to2aand2bafforded diisoproxy Zr complexes3aand3bas a mixture oftransandcis-ß isomers, the latter undergoing fast ?/? isomerization in solution. Addition of B(C6F5)3to2aand2bgave cationic monobenzyl Zr complexes4aand4bwhich have been further converted into cationic alkoxy Zr complexes5a-band6a-bby alcoholysis withiPrOH and (S)-methyl-lactate, respectively. The reaction of the phosphasalen proligands with Ti(NMe2)4proceeded diastereoselectively giving rise to Ti complexes7a-cin octahedral geometry withcis-ß wrapping of the ligand. The complexes have been tested for the ROP ofrac-lactide. The neutral phosphasalen Ti and Zr complexes showed only poor activity probably due to the encumbered and electron donating nature of the phosphasalen ligand. In contrast, the cationic Zr alkoxides5a,6aand6bare effective initiators for the controlled and hetero-selective ROP ofrac-lactide