METHYLENEGLUCOSES - TRANSITION-METAL-CATALYZED SYNTHESIS FROM FORMALINE AND GLUCOSE - IMPORTANCE OF HETEROBIMETALLIC CATALYST

Iron III, ruthenium III and tin (II) chlorides catalyze the synthesis of methyleneglucoses with a yield of 13-20%. Chlorides of remaining me tals and many different iron salts are considerably inferior. The yiel ds of methyleneglucoses is further increased up to 36% when a heterobi metallic system (FeCl3 + SnCl2H2O) is applied as a catalyst. Hypothesi s of the mechanism implies formation of a heterobimetallic complex bri dged by Cl, gem-diol and glucose. The structure of two methyleneglucos es was established as 1,2:5,6-di-O-methylene-alpha glucofuranose and 1 ,2:3,5-di-O-methylene-alpha-glucofuranose.