1→2 Migration and concurrent glycosidation of phenyl 1-thio-α-mannopyranosides via 2,3-O-cyclic dioxonium intermediates
作者:Zunyi Yang、Hongzhi Cao、Jie Hu、Renli Shan、Biao Yu
DOI:10.1016/s0040-4020(02)01452-7
日期:2003.1
phenyl 2,3-O-cyclic ketene acetal- and 2,3-O-thionocarbonyl-1-thio-mannopyranosides with TMSOTf and MeOTf, respectively, gave the corresponding 2,3-O-cyclic dioxonium intermediates, which proceeded via 1→2 migration and concurrent glycosidation in the presence of alcohols to provide the corresponding 2-S-phenyl glycosides stereoselectively. While the former donors were too labile, the latter donors have
分别用TMSOTf和MeOTf处理苯基2,3- O-环烯酮乙缩醛和2,3 - O-硫代羰基-1-硫代甘露吡喃糖苷,得到相应的2,3- O-环二氧on中间体,可通过1→2迁移和同时存在的糖苷在醇的存在下立体选择性地提供相应的2- S-苯基糖苷。前者捐助者过于不稳定,而后者捐助者被证明对目前的目的更为有利。苯基4-的X射线晶体结构ø -甲基-2,3- ö硫羰基-1-硫代-β-α-L-吡喃鼠李糖苷(1),用于本反应的典型供体,并且其端基异构叠氮化物类似物(6提供了在相似条件下无法进行本反应的)。