Amine-Ligated Boryl Radical Enabled Hydrofunctionalization of Styrenes via Halogen-Atom Transfer of Alkyl and Aryl Bromides

Abstract

Herein, we demonstrate an amine-ligated boryl radical mediated halogen-atom transfer (XAT) strategy with alkyl and aryl bromides to construct C(sp ³)–C(sp ³) and C(sp ³)–C(sp ²) bonds, respectively. The first step involves the photocatalytic and decarboxylative generation of amine-ligated boryl radicals from a carboxylic acid containing amine-ligated borane. The resulting amine-ligated boryl radical undergoes XAT with organobromides to generate carbon-centered radicals, which react with styrenes to afford hydrofunctionalized products. Furthermore, this photocatalytic XAT strategy can be applied to synthesize gem-difluorostyrene and 1,1-disubstituted cyclopropane through a radical-polar crossover mechanism.

Key words

halogen-atom transfer - amine-ligated boryl radical - photoredox catalysis - hydrofunctionalization - radical-polar crossover mechanism

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