Highly Stereoselective Synthesis of Primary, Secondary, and Tertiary α-<i>S</i>-Sialosides under Lewis Acidic Conditions
作者:Amandine Noel、Bernard Delpech、David Crich
DOI:10.1021/ol301779e
日期:2012.8.17
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。