ABSTRACT
OBJECTIVE: To stereospecifically synthesize disaccharide galactopyranosyl(α1 → 2) glucopyranoside with protecting groups which are easily and selectively deprotected. METHODS: With D-glucose as a raw material, a donor methyl 3, 4, 6-tri-O-benzoyl-β-D-glucopyranoside was synthesized through acetylation, bromination, methylation, deacetylation, benzylidenation, selective benzoylation, chloroacetylation, and dechloroacetylation; the glucopyranosyl acceptor and a donor isopropyl 3-O-allyl-2-O-benzoyl-4, 6-O-benzylidene-β-D-1-thiogalactopyranoside were reacted at catalysis to achieve an α-coupled product. RESULTS: At the catalysis of TMSOTf/NIS, galactopyranosyl donor and glucopyranosyl acceptor were coupled to afford stereospecifically a full protected disaccharide galactopyranosyl(α1 → 2) glucopyranoside fragment, methyl 3-O-allyl-2-O-benzoyl-4, 6-O-benzylidene-α-D-galactopyranosyl(1 → 2)-3, 4, 6-tri-O-benzoyl-β-D-glucopyranoside. All products were characterized with NMR and MS etc. CONCLUSION: A full protected 1, 2-cis disaccharide fragment was stereospecifically obtained through coupling reaction due to concerted effect of the special configurations of the galactopyranosyl donor and the glucopyranosyl acceptor. Copyright 2012 by the Chinese Pharmaceutical Association.