Gilbert Balavoine

Enantioselective hydrosilylation of acetophenone with rhodium / oxazolines catalysts☆

Abstract N-chelate ligands based on chiral oxazolines are efficient co-catalysts in the enantioselective hydrosilylation of acetophenone with α-naphtylphenylsilane. Enantiomeric excess as up to 80% have been achieved.

Functionalisation of saturated hydrocarbons. part x.1 a comparative study of chemical and electrochemical processes (gif and gif-orsay systems) in pyridine in acetone and in pyridine-co-solvent mixtures

Abstract Six saturated hydrocarbons (cyclohexane, 3-ethylpentane, methylcyclopentane, cis - and trans -decalin and adamantane) were oxidised by the GifIV system (iron catalyst, oxygen, zinc, carboxylic acid) and its electrochemical equivalent (Gif-Orsay system). Results obtained using various solvents (pyridine, acetone, pyridine-acetone mixtures) were similar for both systems. Total or partial replacement of pyridine with acetone affects the selectivity for secondary positions and lowers the ketone/secondary alcohol ratio. The formation of the same ratio of cis - and trans -decal-9-ol from both cis - and trans -decalin clearly demonstrates that tertiary alcohols result from a mechanism essentially radical in nature.

Thioglycosides as Potential Glycosyl Donors in Electrochemical Glycosylation Reactions. Part 1: Their Preparation and Reactivity Toward Simple Alcohols.

Abstract Constant potential electrolysis of several glycosyl donors such as substituted phenyl 2,3,4,6-tetra-O-acetyl, benzoyl or benzyl-1-thio-β-D-gluco or galactopyranosides in dry acetonitrile in the presence of various primary, secondary or tertiary alcohols performed in an undivided cell, gave preferentially β-linked saccharides in moderate to good yields according to the nature of the protective groups on the sugar moiety. 2-Deoxy-2-phthalimido-1-thio-β-D-gluco derivatives gave the β-glucosides selectively in excellent yields. It was found, as expected, that substitution of the phenyl group with methoxy or methyl radicals facilitates the electrochemical glycosylation reaction by lowering the oxidation potentials of the corresponding thioglycosides.

Anodic glycosylation from aryl thioglycosides

Abstract Unprotected aryl thioglucosides undergo electrochemical oxidation in undivided cell at constant moderated potential in the presence of alcohols to give the corresponding glucosides in good yield without any self condensation.

On the oxidation of saturated hydrocarbons with H2O2 in the presence of iron(II)-picolinate or iron(II)−1,10 phenanthroline 2-carboxylate.

Abstract A new catalytic system for highly selective oxidation of saturated hydrocarbons into ketones is described. This system is based on the combination of ferrous picolinate (or 1,10 phenanthroline 2-carboxylate) and H2O2 in pyridine solution. Under these conditions cyclohexane gave mainly cyclohexanone (90%, 22–28% yield based on H2O2) and minor amounts of cyclohexanol .

Tuning of reactivity in epoxidation of alkenes by iron and ruthenium complexes associated to non-porphyrinic ligands

RuCl3·n(H2O) or FeSO4 associated with bipyridyl or substituted phenanthrolines, catalyse the expoxidation of stilbenes by IO4– or ClO–; using phenanthrolines bearing electron donating or withdrawing groups, it is possible to modulate the reactivity of these systems.

The insertion of sulfur into the non-activated CH bond a possible model for penicillin cyclase and biotin synthase

Abstract When cyclohexane is subjected to Gif-type oxidation conditions in the presence of sufficient H 2 S, Na 2 S or (in Gif III ) S 8 , the normal oxidation process is replaced by the formation of dicyclohexyl di- and poly-sulfides.

Iron catalysed insertion of sulfur into the non-activated CH bond.

The reaction of various sulfur reagents (S8, H2S, Na2S, NaHS) with cyclohexane under GifIII, GoAggII and GoAggIII conditions affords the usual oxidation products in competition with cyclohexyl di- and poly-sulfide formation. Other cyclic hydrocarbons behave similary. The sulfation reactions are considered to be biomimetic for the enzymes N synthase and biotin synthase.

On the oxidation of 3-ethylpentane under GifIV and Gif-orsay conditions

Abstract The oxidation of 3-ethylpentane under Gif IV (and GoAgg II ) conditions affords, as major product, 3-acetylpentane and not diethylketone as previously reported. The discrepancy is explained by radical chain autoxidation in presence of a weak tertiary CH bond.

New Catalytic Routes to Preceramic Polymers: Ceramic Precursors to Silicon Nitride and Silicon-Carbide Nitride

Abstract : Pyrolysis of a set of silicon and nitrogen substituted polysilazanes are conducted under a set of standard conditions (5 degrees C/min to 900 degrees C in a nitrogen atmosphere). The apparent ceramic compositions and ceramic yields for pyrolyzed samples of the polysilazanes (Ph(H)SiNH)x, (C6H13(H)SiNH)x, (Me(H)SiNH)x, and (H2SiNMe)x are determined. Preliminary conclusions concerning structure/reactivity relationships are discussed based on the pyrolysis results. Keywords: Polysilazanes, Structure/reactivity relationships, Catalysis, Synthesis, Pyrolysis, New catalytic reactions. Reprints.