Studies on the synthesis of methyl 2,3-anhydro-4,6-O-benzylidene-β-D-allopyranoside and -mannopyranoside, and their reaction with sodium azide

Abstract

Monosulphonation of methyl 4,6-O-benzylidene-β-D-glucopyranoside with methanesulphonyl or toluene-p-sulphonyl chloride gave mixtures of 2-, 3-, and 2,3-esters. This behaviour is in contrast with that of the α-anomer, which gives only the 2-ester. A competitive experiment with the α- and β-anomers showed that the most reactive hydroxy-group was that at C-2 in the α-anomer. Treatment of the β-monosulphonates with alkali gave the appropriate 2,3-anhydro-sugars. Opening of the epoxide rings gave predominantly diaxial products, that is the azido-altroside derivatives. The n.m.r. spectra of the products are discussed in detail.