FURTHER EXAMPLES OF ORTHOESTERIFICATION UNDER KINETICALLY CONTROLLED CONDITIONS - APPLICATION TO THE SELECTIVE ACYLATION OF SUCROSE, MALTOSE AND ALPHA,ALPHA-TREHALOSE

Orthoesterification of sucrose with 1,1-dimethoxyethene under kinetic control gave 4,6-O-methoxyethylidenesucrose in 77% crude yield. Simila r orthoesterification of maltose led essentially after acetylation to 3'-hexa-O-acetyl-4'-6'-O-methoxyethylidenemaltose. Analogous treatment of alpha,alpha-trehalose gave 4',6'-di-O-methoxyethylidene-alpha,alph a-trehalose in 47% yield. The acid-catalyzed opening of these orthoest ers was studied, and these reactions were shown to give disaccharides selectively protected by acetyl groups. (C) 1998 Elsevier Science Ltd.