These are preliminary reports that have not been peer-reviewed. They should not be regarded as conclusive, guide clinical practice/health-related behavior, or be reported in news media as established information. For more information, please see our FAQs.
Preprints are manuscripts made publicly available before they have been submitted for formal peer review and publication. They might contain new research findings or data. Preprints can be a draft or final version of an author's research but must not have been accepted for publication at the time of submission.
revised on 17.04.2020 and posted on 20.04.2020by Edward McClain, Timothy Monos, Mayuko Mori, Joel Beatty, Corey Stephenson
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 the
regeneration of the donor species, representing a rare example 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 evidenced
by the successful multigram-scale trifluoromethylation of methyl N-Boc
pyrrole-2-carboxylate in a continuous flow manifold.