THE ACETOLYSES OF THEALPHAANDBETAMETHYLD-GLUCOPYRANOSIDE TETRAACETATES

Abstract
The acetolyses of the alpha and beta methyl D-glucopyranoside tetraacetates in 1:1 acetic acid – acetic anhydride 0.5 M with respect to sulphuric acid were followed at 25 °C. by isotopic dilution analysis of products isolated after various intervals of time. The reaction of the α-glucoside was found to proceed mainly with inversion of the anomeric center. On the other hand, the β-glucoside was found to undergo acetolysis with retention of configuration concurrent with anomerization. It was shown that the polarimetric changes observed in the course of the reactions could be satisfactorily accounted for on the basis of these reaction routes. Reaction mechanisms are suggested.