SIMPLE SYNTHESIS OF BETA-D-GLUCOSYL ESTERS

Acylation of 2,3,4,6-tetra-0-benzyl-alpha-D-glucopyranose (1) with ben zoyl chloride and triethylamine was found to give nzoyl-2,3,4,6-tetra- O-benzyl-alpha-D-glucopyranose (2) and enzoyl-2,3,4,6-tetra-O-benzyl-b eta-D-glucopyranose (3) in a ratio of 2:9 while acylation of 1 with be nzoyl chloride and pyridine gave 2 and 3 in the ratio 6: 1. Slow addit ion of benzoyl chloride to 1 and triethylamine changed the ratio from 2:9 to 1 : 11. Similar acylation of 1 with either 2- or 4-chlorobenzoy l, acetyl or butanoyl chloride gave the corresponding 1-O-acyl-derivat ives 4, 5, 6 or 7 with high predominance of the beta-anomer. The rate of addition had to be decreased for the aliphatic acyl chlorides to pr ovide good stereoselectivity. 3, 5, 6 and 7 was hydrogenolyzed to give 1-O-benzoyl, 1-O-4-chlorobenzoyl, 1-O-acetyl and 1-O-butanoyl-beta-D- glucopyranoses 8, 9, 10 and 11, respectively.