Visible-Light-Induced Selective Defluoroborylation of Polyfluoroarenes, gem-Difluoroalkenes, and
Wengang Xu1,2, Heming Jiang3, Jing Leng1,4
1Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.
Abstract:
Fluorinated organoboranes serve as versatile synthetic precursors for the preparation of value-added fluorinated organic compounds. Recent progress has been mainly focused on the transition-metal catalyzed defluoroborylation. Herein, we report a photocatalytic defluoroborylation platform through direct B-H activation of N-heterocyclic carbene boranes, through the synergistic merger of a photoredox catalyst and a hydrogen atom transfer catalyst. This atom-economic and operationally simple protocol has enabled defluoroborylation of an extremely broad scope of multifluorinated substrates including polyfluoroarenes, gem-difluoroalkenes, and trifluoromethylalkenes in a highly selective fashion. Intriguingly, the defluoroborylation protocol can be transition-metal free, and the regioselectivity obtained is complementary to the reported transition-metal-catalysis in many cases.
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