Efficient stereoselective synthesis of 1-thio-beta-mannopyranosides

An efficient method for the synthesis of 1-thio-beta -mannopyranosides is reported. This method employs the simple, easy-to-make 2,3,4,6-tetra-O-acetyl-1-S-acetyl-1-thio-beta -D-mannopyranose as starting material to conduct an in situ selective de-S-acetylation, and subsequent S(N)2 reaction with an acceptor bearing a leaving group. The high nucleophilicity and slow anomerization of the intermediate thiol allows the synthesis of 1-thio-beta -mannopyranosides in a simple and practical manner.