Georges Bram

Organic syntheses without solvent: base-catalysed ester interchange

Abstract Ester interchange of methyl or ethyl carboxylic esters by primary or secondary alcohols is carried out effectively when solid-liquid phase transfer catalysis (PTC) is achieved in the absence of added organic solvent. Vinyl and isopropenyl acetates undergo ester interchange, even in the absence of PTC catalyst, with primary alcohols and phenols.

Surface enhanced enantiodifferentiation in reactions of chiral acetoacetates

Abstract The stereoselectivity of the alkylation of chiral acetoacetates by racemic secondary alkyl halides changes when the reaction is carried out on a solid support; the change can be interpreted in terms of a model involving surface imposed conformational restrictions.

Highly selective benzylations of β-naphthoxide anion in heterogeneous media

Abstract Each of the four products resulting from the benzylation of the ambident β-naphthoxide anion can be efficiently and selectively obtained in mild an economical conditions by a judicious choice of the solid base: LiOH, LiOtBu or KOH-Aliquat.

The difficult marriage of theory and French organic chemistry in the 20th century

Abstract In the first half of this century, the postivism of many French organic chemists, who were reluctant to speculate about phenomena not directly observable, generated a certain scepticism for theories, with many unfortunate consequences. Thus, reaction mechanisms were not taught until the late 1950s and organic synthesis of complex molecules was consequently hampered. MO theory was practically ignored until 1965, when Woodward and Hoffmann published their epoch-making papers. The situation was restored in an astonishlingly short time, but the marriage between theory and French organic chemistry was, and still is, a difficult one.

Effet de l'eau et d'autres additifs sur l'alkylation de KCN en transfert de phase solide-liquide sans solvant.

Abstract The alkylation of KCN by solid-liquid phase transfer catalysis without added solvent is optimal when a definite amount of water is added. The efficiencies of ten other additives are compared with those of water.