A. Kergomard

Reduction microbiologique d'aldehydes α, β-ethyleniques par Beauveria sulfurescens

Abstract αβ-unsaturated aldehydes are reduced by Beauveria sulfurescens , giving a mixture of the corresponding ethylenic and saturated alcohols. Optically active saturated alcohols have the ( S )-configuration.

Microbial reduction of α,β-unsaturated carbonyl compounds: A general property?

Abstract The double bonds of cyclohexenone and methylcyclohexenone were reduced by a strain of Clostridium and by various strains of Streptomyces . These results and those observed previously show that this reduction is widespread among microorganisms.

Reduction of 1,1-dideuterio-2-methyl-2-penten-1-ol by beauveria sulfurescens. Mechanism of the microbiological reduction of α,β-unsaturated ald

Abstract Reduction of 1,1-dideuterio-2-methyl-2-penten-1-ol by Beauveria sulfurescens leads to the corresponding saturated mono-deuterated alcohol. This result allows the understanding of the mechanism of the microbiological reduction of α,β-unsaturated alcohols by B. sulfurescens. Thus, the stereochemical rule previously established for the reduction of α,β-unsaturated ketones can be carried out to the reduction of unsaturated aldehydes by B. sulfurescens.

Réductions microbiologiques stéréosélectivés des Δ-4 céto-3 stéroïdes

Abstract In anaerobic conditions the reduction of Δ-4 3-keto steroids by Clostridium paraputrificum leads either to the 3-keto 5β compounds or to the corresponding 3α-hydroxytetrahydro-5β derivatives. This stereospecific bioconversion of αβ-unsaturated 3-keto steroids is shown to be directed by the substrate concentration. The conversion of Δ-4 cholestenone to coprostanone or coprostanol is not observed.

Microbiological synthesis and circular dichroism of optically active 2-deuterio-cycloalkanones

Abstract Optically active 2-deuterio-cyclopentanone and 2-deuterio-cyclohexanone have been prepared by microbiological reduction of 2-deuterio α,β-unsaturated cyclic ketones by Beauveria sulfurescens .

Multifunctional catalysis XI : Asymmetric catalysis of the mutarotation of tetramethylglucose by optically active phosphinothioic acids.

Abstract Catalytic activities of R(+) and racemic t-butylphenylphosphinothioic acids on the mutarotation of 2,3,4,6 tetramethyl-d-glucose are studied in benzene.

Isomerisation de la Δ5 cholestenone catalysee par quelques oxyacides phosphores

Abstract The isomerisation of Δ5 cholestenone catalysed by some oxyacids containing phosphorus has been studied. A reaction mechanism is outlined, which agrees with that already proposed using carboxylic acids, two molecules of the catalyst being involved. Phosphorous oxyacids are better catalysts than carboxylic acids. The kinetic law is complex because of the high polymerisation of these acids. The polymerisation constants are given for the first time.

Microbiological synthesis of optically active 3-deuterio-cycloalkanones

Optically active 3-deuterio-cyclopentanone and 3-deuterio-cyclohexanone have been prepared by microbiological reduction of 3-deuterio αβ-unsaturated cyclic ketones by Beauveria sulfurescens.

Reduction of (αβ-Unsaturated Ketones by Various Fungi

αβ-Unsaturated ketones were reduced by selected fungi (which are known steroid hydroxylators) incubated under limited aerobic conditions.

Multifunctional catalysis—X: “Tailor-made” catalysts for the isomerisation of Δ-5 cholestenone

Abstract “Tailor-made” dicarboxylic acids and dihydroxynaphthalene-triethylamine complexes catalyse the isomerisation of Δ-5-cholestenone. The reaction is faster and of lower kinetic order than with simple bifunctional catalysts; the activation entropy is more favourable, but the activation enthalpy is higher, due possibly to steric and electronic interference, between the catalysing functions, which are absent in the corresponding isomerases.