Visible-Light-Mediated Umpolung Reactivity of Imines: Ketimine Reductions with Cy₂NMe and Water

Abstract

A novel carbanionic reactivity of imines mediated by photoredox catalysis is demonstrated. The umpolung imine reactivity is exemplified by proton abstraction from water as a key step in the reduction of benzophenone ketimines to amines (up to 98% yield). Deuterium is introduced into amines efficiently using D₂O as an inexpensive deuterium source (≥95% D ratio). The mechanism of this unusual transformation is probed.