STUDIES OF THE SELECTIVE SILYLATION OF METHYL α- AND β-D-ALDOHEXOPYRANOSIDES: STABILITY OF THE PARTIALLY PROTECTED DERIVATIVES IN POLAR SOLVENTS

Article abstract of DOI:10.1016/0008-6215(87)85005-X

Treatment of methyl α- (1) and β-D-glucopyranosides, methyl α- (3) and β-D-galactopyranosides, and methyl α-D-mannopyranoside (5) with 2,3, or 4 mol.equiv. of tert-butyldimethylsilyl (TBDMS) chloride under two conditions afforded mixtures of TBDMS ethers which were identified.The following compounds were isolated in synthetically useful yields, the 2,6-di-TBDMS ether of 1 (70percent), the 2,6-di- and 2,3,6-tri-TBDMS ethers of 3 (84percent and 57percent, respectively), and the 2,6-di and 3,6-di-TBDMS ethers of 5 (50percent and 80percent, respectively).In dipolar solvents, no migration of the TBDMS groups was detected between partially silyated hydroxyl groups, but the addition of a base (triethylamine or imidazole) caused migration to vicinal cis positions.