Asymmetric reduction of acetophenone using α,α-disubstituted aziridinemethanols and borane

A series of α,α-disubstituted aziridinemethanols have been designed and synthesized as chiral auxiliaries for the enantioselective reduction of acetophenone. Some of them catalyzed the reduction with excellent ee (up to 97%) under more facile reaction conditions. Furthermore, the results showed that α,α-disubstituted aziridinemethanols with electron-withdrawing groups led to much higher enantioselectivity than those with electron-donating groups, which allowed the rational modification of catalyst structure to achieve optimal enantioselectivity.

Graphical abstractEnantioselective reduction of acetophenone using α,α-disubstituted aziridinemethanols as catalysts proceeded with high ee values under more facile reaction conditions. Aziridinemethanols α,α-disubstituted with electron-withdrawing groups displayed much higher enantioselectivity than those α,α-disubstituted with electron-donating groups under the same conditions of solvent, temperature and the amount of catalyst, which allowed the rational modification of catalyst structure to achieve optimal enantioselectivity.Figure optionsDownload full-size imageDownload as PowerPoint slide