THE PREPARATION AND CONFIGURATIONS OF TRI-O-ACETYL-α-D-GLUCOPYRANOSE 1,2-(ORTHOESTERS)

Abstract

Reaction of tri-O-acetyl-2- O-acyl (acetyl, benzoyl, pivalyl, and methoxycarbonyl)-α-D-glucopyranosyl halides with a variety of alcohols in sym-collidine containing a tetraalkylammonium halide gave the 1,2-orthoesters in near quantitative yields. In each case one of the two diastereoisomeric orthoesters was obtained in high yield and was shown by application of n.m.r. spectroscopy to be that isomer which has the alkoxy group on the dioxolan ring trans to the pyranose ring (exo-configuration). Participation of a methoxycarbonyloxy group allowed the preparation of a 1,2-(dimethyl orthocarbonate). 1,2-(Phenyl orthoacetates) were prepared.