Nouvelles avancées pour la synthèse d’éthers insaturés dérivés de polyols par transformation du butadiène

National audienc

Synthesis of C4 chain glyceryl ethers via nickel-catalyzed butadiene hydroalkoxylation reaction

International audienceThe catalytic hydroalkoxylation of butadiene with glycerol has been performed for the first time thanks to the use of nickel catalysts and an appropriate solvent. Optimization of the reaction conditions allowed obtaining 100% glycerol conversion into a mixture of glyceryl mono- and dibutenyl ethers. The experimental protocols used involved batch experiments or continuous feeding of butadiene at atmospheric pressure. The reaction has then been scaled up to produce multigrams of each pure monoethers and diethers according to simple decantation/distillation procedures. The ethers were further hydrogenated to their corresponding alkyl glyceryl ethers

Enantioselective nickel catalyzed butadiene hydroalkoxylation with ethanol: from experimental results to kinetics parameters

International audienceThe enantioselective hydroalkoxylation of butadiene with ethanol has been performed in the presence of nickel-based catalysts and chiral diphosphine ligands. Ee’s up to 77% could be obtained from the use of atropoisomeric chiral ligands such as Segphos. The kinetics parameters of the reaction were determined using a qualitative kinetic model to better explain the l/b isomerization and racemization processes observed for long reaction times

Catalytic Chain Transfer (co-)Polymerization: Unprecedented Polyisoprene CCG and a New Concept to Tune the Composition of a Statistical Copolymer

International audienceBorohydrido-halflanthanidocene/dialkylmagnesium combinations are found to be powerful catalytic systems for the chain transfer polymerization of isoprene and its copolymerization with styrene. A behavior close to a lanthanide catalyzed polyisoprene chain growth on magnesium is reported. Transmetalation is further shown to occur in the course of the statistical copolymerization of isoprene and styrene. For the same monomer feed, the amount of styrene inserted in the copolymer can be increased by a factor 3 using 10 equiv. dialkylmagnesium versus 1 in the range of our experimental conditions. Chain transfer in the course of a metal catalyzed statistical copolymerization may thus be viewed as a new and original way for the control of the composition of a copolymer

Preparation of pyridinyl aryl methanol derivatives by enantioselective hydrogenation of ketones using chiral Ru(diphosphine)(diamine) complexes. Attribution of their absolute configuration by 1H NMR spectroscopy using the Mosher's reagent

International audienc

Improving manufacturing of PolyVinyl Chloride via catalytic decomposition of peroxides

National audienc

Improved reactivity in the conversion of nitrile-functionalized olefins by metathesis

International audienceIn this contribution, we study the conversion of a bio-sourced unsaturated fatty ester by cross-metathesis with nitrile-functionalized olefinic partners (acrylonitrile and crotonitrile). A switch from terminal to internal olefins leads to higher conversion. This is in part rationalized by involvement of a more stable ruthenium ethylidene species with crotonitrile. A new carbenic complex forms upon reaction with the nitrile-functionalized olefins, that is also catalytically active

Catalytic Synthesis and Asymmetric Reduction of Pyridylglyoxylic Amides and Esters

International audienceThe preparation of 2‐pyridyl‐ and 4‐pyridylglyoxylic esters and amides in moderate to high yields via palladium‐catalyzed double carbonylation of 2‐iodo‐ and 4‐iodopyridines is reported. The effect of temperature, CO pressure, solvent, nature and concentration of nucleophile, nature of catalyst precursor, and substituents on iodopyridines has been investigated. The reduction of 4‐pyridylglyoxylate esters into the corresponding α‐hydroxy esters via ruthenium‐catalyzed asymmetric hydrogenation or using alpine‐borane proceeded in high yields but poor enantioselectivity. The results for the carbonylation and the hydrogenation catalytic processes are discussed in terms of electronic effects induced by the pyridyl ring

Synthesis of pyridylglyoxylic acid derivatives via a palladium-catalysed double carbonylation of iodopyridines

International audience4-Iodopyridiens react with CO and HNEt2 orin the presence of a catalytic amount of PdCl2(PPh3)2 to give the corresponding α-keto amides and esters in fair to high yields.4-iodopyridines are transformed into the corresponding α-keto amides and esters in moderate to high yields