Highly diastereoselective synthesis of α-difluoromethyl amines from N-tert-butylsulfinyl ketimines and difluoromethyl phenyl sulfone.

The first highly efficient and stereoselective difluoromethylation of structurally diverse N-tert-butylsulfinyl ketimines has been achieved with an in situ generated PhSO(2)CF(2)(-) anion, which provides a powerful synthetic method for the preparation of a variety of structurally diverse homochiral α-difluoromethyl tertiary carbinamines, including α-difluoromethyl allylic amines and α-difluoromethyl propargylamines. The stereocontrol mode of the present diastereoselective difluoromethylation of ketimines was found to be different from that of other known fluoroalkylations of N-tert-butylsulfinyl aldimines, which suggests that a cyclic six-membered transition state may be involved in the reaction.