Studies of the selective silylation of methyl α- and β-d-aldohexopyranosides: stability of the partially protected derivatives in polar solvents
作者:Thérèse Halmos、Roland Montserret、Jean Filippi、Kostas Antonakis
DOI:10.1016/0008-6215(87)85005-x
日期:1987.12
Treatment of methyl .alpha.- (1) and .beta.-D-glucopyranosides, methyl .alpha.- (3) and .beta.-D-galactopyranosides, and methyl .alpha.-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 (70%), the 2,6-di- and 2,3,6-tri-TBDMS ethers of 3 (84% and 57%, respectively), and the 2,6-di- and 3,6-di-TBDMS ethers of 5 (50% and 80%, respectively). In dipolar solvents, no migration of the TBDMS groups was detected between partially silylated hydroxyl groups, but the addition of a base (triethylamine or imidazole) caused migration to vicinal cis positions.