Design and Implementation of a Catalytic Electron Donor–Acceptor Complex Platform for Radical Trifluoromethylation and Alkylation
Edward J. McClain, Timothy M. Monos, Mayuko Mori, Joel W. Beatty, Corey R. J. Stephenson
Abstract
Electron donor–acceptor (EDA) complexes can controllably generate radicals under mild conditions through selective photoexcitation events. However, unproductive reactivity from fast deactivation of the photoexcited complexes through back electron transfer has slowed the development of EDA complexes in synthetic methodology. Here, we disclose the study of EDA complexes derived from 2-methoxynaphthalene donor and acylated ethyl isonicotinate N-oxide acceptor that undergo a fast N–O bond fragmentation event upon photoexcitation. This reaction design not only overcomes the limitations of back electron transfer but also enables regeneration of the donor species, representing a rare example of EDA photochemistry in a catalytic regime. The synthetic utility is demonstrated through visible light-driven radical trifluoromethylation and Minisci alkylation reactions. The scalability of the EDA complex-promoted reaction is evidenced by the successful multigram-scale trifluoromethylation of methyl N-Boc pyrrole-2-carboxylate in a continuous flow manifold.