Glycosylation of secondary alcohols such as cholesterol, methyl 2,4,6-tri-O-benzylgalactopyranoside, and 2-deoxy-2,3-dehydro-NeuAc methyl ester with a new glycosyl donor, 2β,3α-dibromo-2-deoxy-NeuAc methyl ester, selectively gave the corresponding β-glycosides in high yields. The 3α-bromo-glycosides were debrominated with tri-n-butylstannane to the corresponding glycosides, which were deprotected to
仲醇如
胆固醇、甲基 2,4,6-tri-O-benzylgalactopyranoside 和 2-deoxy-2,3-dehydro-NeuAc 甲酯与新的糖基供体 2β,3α-dibromo-2-deoxy 的糖基化-NeuAc 甲酯,选择性地以高产率得到相应的 β-糖苷。3α-
溴-糖苷用三正
丁基锡烷脱
溴为相应的糖苷,将其脱保护得到具有β-NeuAc的游离糖苷。