Marc Larcheveque

L'eldanolide, phéromone des glandes alaires de la pyrale de la canne à sucre, eldana saccharina (wlk.): structure et synthèse de ses deux énantiomères

Abstract The isolation and structure determination of eldanolide, the wing gland pheromone of the male African Sugar Cane Borer, Eldana saccharina (Wlk.) is described. The absolute configuration was determined as (3S, 4R) by comparison of the CD spectra of the natural pheromone with both synthetic enantiomers.

Absolute configuration of eldanolide, the wing gland pheromone of the male African sugar cane borer, Eldana saccharina (Wlk.) syntheses of its (+) and (−) enantiomers.

Abstract Eldanolide 1 , a novel terpenoid lactone pheromone, was shown to have (3S,4R) configuration by synthesis of both enantiomers and comparison of their CD with the natural pheromone.

A simple preparation of R or S glycidic esters; Application to the synthesis of enantiomerically pure α-hydroxyesters.

Abstract The simple preparation of enantiomerically pure α-hydroxyesters by the regioselective reaction of lithio and magnesiocuprates with glycidic esters 3 or 3 ′ readily available from serine is described.

Synthèse énantiospécifique du 5-hexadécanolide, phéromone de «Vespa orientalis»

Abstract A synthetic scheme was elaborated to prepare (R)(+) δ-n-hexa-decanolactone 10 in 8 steps from (L)-glutamic acid.

Synthesis of (E)β,γ-unsaturated α-aminoacids by rearrangement of allyltrichloroacetimidates

Abstract Pure (E)-β,γ-unsaturated α-aminoacids of high enantiomerical purity were synthesized by Pd(II) catalyzed rearrangement of trichloroacetimidates derived from optically pure monoprotected diallylalcohols. After cyclisation of the resulting N-trichloracetyl allylic amines into unsaturated oxazolidinones, these intermediates were transformed into N-Boc-aminoalcohols and oxidized with molecular oxygen in the presence of platinum.

A Study of the Stereocontrolled Reduction of Aliphatic β-Ketoesters by Geotrichum candidum

The conditions necessary to reduce stereoselectively aliphatic beta-ketoesters by G. candidum have been investigated. Ageing of the mycelium allowed a practical preparation of optically pure (R)-ethyl 3-hydroxybutanoate, as a result of stereoselective reduction, enantioselective metabolism and stereoisomer interconversion. The stereoconversion of 3S-hydroxybutanoate into the 3R-enantiomer via 3-oxoester formation has been demonstrated to be a determining factor in the building of the optical purity of the resulting product. Enantioselective preparations of higher homologous 3R-hydroxyesters are described.

Aminoacids as Chiral Synthons1: Preparation of Enantiomerically Pure (R) and (S) Malic Acids and its Application to the Synthesis of 3-Hydroxy 4-Butanolide

Abstract Malic acid has been proved to be an extremely valuable chiral synthon for enantiospecific synthesis of complex molecules such as monensin2, amphotericin B3, variou s hydroxytetrahydrofurans4, lactones5,6 and pheromones7. However the (S) isomer only is easily available8; the (R) isomer is more difficult to obtain and is generally prepared by a synthetic way9.

Diastereo- and enantioselective microbiological reduction of 2-methyl 3-oxoalkanoates

Abstract Reduction of 2-methyl 3-oxobutanoate or pentanoate by several fungal strains gave essentially the corresponding and anti (2S,3S)-hydroxyesters in high optical purity.

The microbial reduction of 2-chloro-3-oxoesters

Abstract Several aliphatic or aromatic 2-chloro-3-oxoesters are stereoselectively reduced by yeast or fungal strains, affording in fair to good yield and high enantiomeric excess some of the respective 2-chloro-3-hydroxyester stereoisomers.

Asymmetric alkylation of chiral N,N-disubstituted amides

Abstract Chiral N,N -disubstituted amides may be readily synthesized by reacting an anhydride with l - or d -ephedrine. The alkylation of the carbanions derived from these amides affords α-substituted chiral ketones and acids after cleavage. A study of the reaction characteristics indicates that the nature of the counter ion (Li or Mg) is the critical factor in the asymmetric synthesis. In this way, ( S )-(+)-4-methyl-3-heptanone, an alarm pheromone of “Atta Texana”, was synthesized in 81% enantiomeric excess.