C-3 with a carbamate group undergo, upon dehydration, a prompt allyl cyanate to isocyanate rearrangement to the isomeric N-glycosyl isocyanates, which give N-glycosyl carbamates and ureas by one-pot addition of alcohols or amines. The rearrangement occurs with complete stereoselectivity via a [3,3]-sigmatropic mechanism, affording α- or β-linked amines depending on the configuration at C-3 of the carbohydrate
在 C-3 处被
氨基甲酸酯基团取代的糖醇在脱
水后会迅速发生
氰酸烯
丙酯到
异氰酸酯重排,形成异构的N-糖基
异氰酸酯,通过一锅法添加醇或胺得到N-糖基
氨基甲酸酯和
脲。重排通过 [3,3]-sigmatropic 机制以完全立体选择性发生,根据
碳水化合物 C-3 的构型提供 α- 或 β- 连接的胺。