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Base-Directed Photoredox Activation of C-H Bonds by PCET.

ABSTRACT: Photoredox catalysis using proton-coupled electron transfer (PCET) has emerged as a powerful method for bond transformations. We previously employed traditional chemical oxidants to achieve multiple-site concerted proton-electron transfer (MS-CPET) activation of a C-H bond in a proof-of-concept fluorenyl-benzoate substrate. As described here, photoredox oxidation of the fluorenyl-benzoate follows the same rate constant vs driving force trend determined for thermal MS-CPET. Analogous photoredox catalysis enables C-H activation and H/D exchange in a number of additional substrates with favorably positioned bases. Mechanistic studies support our hypothesis that MS-CPET is a viable pathway for bond activation for substrates in which the C-H bond is weak, while stepwise carboxylate oxidation and hydrogen atom transfer likely predominate for stronger C-H bonds.

SUBMITTER: Ener ME

PROVIDER: S-EPMC7275901 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature

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Base-Directed Photoredox Activation of C-H Bonds by PCET.

Ener Maraia E ME Darcy Julia W JW Menges Fabian S FS Mayer James M JM

The Journal of organic chemistry 20200515 11

Photoredox catalysis using proton-coupled electron transfer (PCET) has emerged as a powerful method for bond transformations. We previously employed traditional chemical oxidants to achieve multiple-site concerted proton-electron transfer (MS-CPET) activation of a C-H bond in a proof-of-concept fluorenyl-benzoate substrate. As described here, photoredox oxidation of the fluorenyl-benzoate follows the same rate constant <i>vs</i> driving force trend determined for thermal MS-CPET. Analogous photo ...[more]

PMID: 32364382

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