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A Triple Photoredox/Cobalt/Brønsted Acid Catalysis Enabling Markovnikov Hydroalkoxylation of Unactivated Alkenes

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journal contribution
posted on 2022-04-27, 17:11 authored by Masanari Nakagawa, Yuki Matsuki, Kazunori Nagao, Hirohisa Ohmiya
We demonstrate Markovnikov hydroalkoxylation of unactivated alkenes using alcohols through a triple catalysis consisting of photoredox, cobalt, and Brønsted acid catalysts under visible light irradiation. The triple catalysis realizes three key elementary steps in a single catalytic cycle: (1) Co­(III) hydride generation by photochemical reduction of Co­(II) followed by protonation, (2) metal hydride hydrogen atom transfer (MHAT) of alkenes by Co­(III) hydride, and (3) oxidation of the alkyl Co­(III) complex to alkyl Co­(IV). The precise control of protons and electrons by the three catalysts allows the elimination of strong acids and external reductants/oxidants that are required in the conventional methods.