phosphates of either anomeric configuration are excellent donors for the formation of α-S-sialosides at −78 °C in dichloromethane with primary, secondary, and tertiary thiols including galactose 3-, 4-, and 6-thiols. The reactions, which proceed under typical Lewis acid promoted glycosylation conditions, are highly α-selective and do not suffer from competing elimination of the phosphate.
两种端基构型的N-乙酰基4- O,5- N-
恶唑烷酮保护的
唾液酸磷酸酯都是出色的供体,可在-78°C的
二氯甲烷中与伯,仲和叔
硫醇(包括半
乳糖3-)一起形成α- S-
唾液酸。 ,4-和6-
硫醇。在典型的
路易斯酸促进的糖基化条件下进行的反应是高度α-选择性的,并且不会竞争性地消除
磷酸盐。