A Convenient Preparation Method for Benzophenone Imine Catalyzed by Tetrabutylammonium Fluoride

Benzophenone imine is a useful ammonia equivalent in the Buchwald-Hartwig amination and an important intermediate for the synthesis of N-protected primary amines. However, the conventional synthesis of benzophenone imine requires stoichiometric amounts of metal reagents or high-pressure conditions. Herein we report a facile method for preparing benzophenone imine to enhance its potential utility. The reaction is performed by mixing commercially available benzophenone and bis(trimethylsilyl)amine in the presence of a catalytic amount of tetrabutylammonium fluoride at ambient temperature and pressure and can be readily applied to a multigram-scale synthesis even in a standard academic laboratory setup. Preliminary mechanistic studies and the application of the reaction to one-pot benzophenone imine synthesis/Buchwald-Hartwig amination are also reported.