Methyl-4,6-O-propylidene-u-~-glucoside was first prepared by R. L. MELLIES, C. L. MEHLTRETTER and C. E.REST (1) in 1951 with a procedure involving suspension of methyl-u-D-glucoside in a large excess of propionaldehyde in the presence of concentrated hydrochloric acid (heterogeneous conditions). In these conditions the main product is methyl-2,3-oxidodipropylidene-4,6-propylidene-a-~-glucoside and only a 23O1, yield of methyl-4,6-propylidenea-D-glucoside was obtained. A similar method wm used by