Dynamic Asymmetric Diamination of Allylic Alcohols through Borrowing Hydrogen Catalysis: Diastereo‐Divergent Synthesis of Tetrahydrobenzodiazepines

Abstract

We present herein an unprecedented, catalytic enantioconvergent diamination of racemic allylic alcohols with the construction of two C‐N bonds and 1,3‐nonadjacent stereocenters. This iridium/chiral phosphoric acid cooperative catalytic system operates through an atom‐economical borrowing hydrogen amination/aza‐Michael cascade, and converts readily available phenylenediamines and racemic allylic alcohols to 1,5‐tetrahydrobenzodiazepines in high enantioselectivity. An intriguing solvent‐dependent switch of diastereoselectivity was also observed. Mechanistic studies suggested a dynamic kinetic resolution process involving racemization through a reversible Michael addition, making the last step of asymmetric imine reduction the enantiodetermining step of this cascade process.