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.