PRODUCTION OF PYRANOSIDE DERIVATIVE BEARING GEMINAL DIMETHYL GROUP

PROBLEM TO BE SOLVED: To provide a method for producing the subject derivative by gem- dimethylation of the pyranoside ring carbon atom of a saccharide derivative without affecting the other carbon atoms' asymmetry (steric configuration) and functional groups on the pyranoside ring of the saccharide derivative and also under mild conditions. SOLUTION: This method for producing the aimed gem-dimethyl group- bearing pyranoside derivative comprises conjugated C-methylation of the pyranoside ring carbon atom as β-carbon to an α,β-unsaturated electron- attractive group not directly linked to the pyranoside ring; for example, methyl-4,6-O-benzylidene-3-deoxy-2-O: 3,3-di-C-trimethyl-α-D-ribohexopyranoside as one of the aimed derivatives is obtained from methyl-4,6-O-benzylidene-2-O- methyl-α-D-ribohexopyranoside-3-urose via the corresponding α,β-unsaturated sulfone derivative.