Synthesis of 2,3-Anhydro Glycosyl Phosphonates

Abstract

The synthesis of dimethyl 6-O-acetyl-2,3-anhydro-α-D- mannopyranosylphosphonates and the corresponding α- and β- allo derivatives is described. Dimethyl 4,6-di-O-acetyl-2,3-dideoxy-D-erythro-hex-2-enopyranosylphosphonates, although unreactive towards normal epoxidizing agents (3-chloroperoxybenzoic acid, trifluoroperoxyacetic acid, etc), underwent smooth epoxidation with hydrogen peroxide in the presence of sodium tungstate or dodecatungstophosphoric acid. An interesting regiospecific deacetylation of the 4-acetate occurred under these conditions. The structures of these anhydro glycosyl phosphonates were determined by ¹H and ¹³C n.m.r. spectroscopy, and confirmed by X ray structural analysis in the case of dimethyl 6-O-acetyl-2,3-anhydro-α-D-mannopyranosylphosphonate , and of dimethyl 6-O-acetyl-2,3-anhydro-β-D-allopyranosylphosphonate.