Asymmetric Paired Electrolysis: Enantioselective Alkylation of Sulfonylimines via C(sp3)-H Functionalization.

ABSTRACT

Enantioselective transformation of ubiquitous C(sp3)-H bonds into three-dimensional chiral scaffolds is of longstanding interest to synthetic chemists. Herein, an asymmetric paired electrolysis enables a highly efficient and sustainable approach to the enantioselective alkylation of sulfonylimines via C(sp3)-H functionalization. In this protocol, anodic oxidation for benzylic radical formation and Lewis acid-catalyzed sulfonylimine reduction on the cathode were seamlessly cross-coupled (up to 88 % yield). Enantioenriched chiral amines containing a tetrasubstituted carbon stereocenter are accessed with high enantioselectivity (up to 96 % ee). Mechanistic studies suggest that the amine generated in situ could serve as a base to deprotonate phenols and decrease the oxidation potential of the reaction, allowing phenols with lower potentials to be preferentially oxidized.