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Umpolung Difunctionalization of Carbonyls via Visible-Light Photoredox Catalytic Radical-Carbanion Relay.

ABSTRACT: The combination of photoredox catalysis with the Wolff-Kishner (WK) reaction allows the difunctionalization of carbonyl groups by a radical-carbanion relay sequence (photo-Wolff-Kishner reaction). Photoredox initiated radical addition to N-sulfonylhydrazones yields ?-functionalized carbanions following the WK-type mechanism. With sulfur-centered radicals, the carbanions are further functionalized by reaction with electrophiles including CO2 and aldehydes, whereas CF3 radical addition furnishes a wide range of gem-difluoroalkenes through ?-fluoride elimination of the generated ?-CF3 carbanions. More than 80 substrate examples demonstrate the broad applicability of this reaction sequence. A series of investigations including radical inhibition, deuterium labeling, fluorescence quenching, cyclic voltammetry, and control experiments support the proposed radical-carbanion relay mechanism.

SUBMITTER: Wang S

PROVIDER: S-EPMC7252948 | biostudies-literature | 2020 Apr

REPOSITORIES: biostudies-literature

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Umpolung Difunctionalization of Carbonyls via Visible-Light Photoredox Catalytic Radical-Carbanion Relay.

Wang Shun S Cheng Bei-Yi BY Sršen Matea M König Burkhard B

Journal of the American Chemical Society 20200413 16

The combination of photoredox catalysis with the Wolff-Kishner (WK) reaction allows the difunctionalization of carbonyl groups by a radical-carbanion relay sequence (photo-Wolff-Kishner reaction). Photoredox initiated radical addition to N-sulfonylhydrazones yields α-functionalized carbanions following the WK-type mechanism. With sulfur-centered radicals, the carbanions are further functionalized by reaction with electrophiles including CO2 and aldehydes, whereas CF3 ...[more]

PMID: 32233431

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