A novel phosgene-free procedure for the synthesis of α-isocyanato carboxylic acid esters starting from α-amino acid esters has been achieved. The isocyanates are obtained enantiomerically pure (>99% ee) by a DMAP-catalyzed isocyanation with di-tert-butyl dicarbonate, which proceeds in 10 min at room temperature. In situ derivatization of the isocyanates by reaction with amines and alcohols affords the corresponding enantiopure ureas and carbamates.
以δ-
氨基酸酯为起点合成δ-异
氰酸羧酸酯的不含
光气的新方法已经实现。通过
DMAP 催化与
二碳酸二叔丁酯的
异氰酸酯化反应,可在室温下 10 分钟内获得对映体纯度大于 99% 的
异氰酸酯。
异氰酸酯通过与胺和醇反应进行原位衍生,可得到相应的对映体
脲和
氨基甲酸酯。