NHC-Catalyzed Single-Electron Oxidation and Alkylation of Imines: Alkene Difunctionalization and Dehydrogenative Coupling

The development of a catalytic activation model enables
the innovation
of synthetic methods toward functional molecules. Recently, radical
NHC catalysis has attracted considerable attention and has achieved
numerous successes. It unlocks the potential to activate inert substrates
and access valuable ketones that are beyond the reach of conventional
methods. However, this strategy has so far been limited to the activation
of carbonyl compounds for ketone synthesis. In contrast, the radical
activation of imines under NHC catalysis for facile synthesis remains
an unmet challenge. Herein, we report the NHC-catalyzed single-electron
oxidation and alkylation of imines. Various agents, including Togni
reagent, α-iododifluoroacetate, phenyl(difluoroiodomethyl)sulfone,
perfluoroalkyl iodide, and peroxyester, proved to be effective single-electron
oxidants. This versatility enabled the development of both alkene
difunctionalization and a dehydrogenative coupling reaction. Preliminary
mechanistic studies supported the proposed reaction pathway. The utility
of this method is demonstrated through the late-stage functionalization
of pesticide-related molecules and the divergent transformation of
the products.