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Photocatalytic Reductive Radical-Polar Crossover for a Base-Free Corey-Seebach Reaction.

ABSTRACT: A metal-free generation of carbanion nucleophiles is of prime importance in organic synthesis. Herein we report a photocatalytic approach to the Corey-Seebach reaction. The presented method operates under mild redox-neutral and base-free conditions giving the desired product with high functional group tolerance. The reaction is enabled by the combination of photo- and hydrogen atom transfer (HAT) catalysis. This catalytic merger allows a C-H to carbanion activation by the abstraction of a hydrogen atom followed by radical reduction. The generated nucleophilic intermediate is then capable of adding to carbonyl electrophiles. The obtained dithiane can be easily converted to the valuable ?-hydroxy carbonyl in a subsequent step. The proposed reaction mechanism is supported by emission quenching, radical-radical homocoupling and deuterium labeling studies as well as by calculated redox-potentials and bond strengths.

SUBMITTER: Donabauer K

PROVIDER: S-EPMC7589390 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature

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Photocatalytic Reductive Radical-Polar Crossover for a Base-Free Corey-Seebach Reaction.

Donabauer Karsten K Murugesan Kathiravan K Rozman Urša U Crespi Stefano S König Burkhard B

Chemistry (Weinheim an der Bergstrasse, Germany) 20200917 57

A metal-free generation of carbanion nucleophiles is of prime importance in organic synthesis. Herein we report a photocatalytic approach to the Corey-Seebach reaction. The presented method operates under mild redox-neutral and base-free conditions giving the desired product with high functional group tolerance. The reaction is enabled by the combination of photo- and hydrogen atom transfer (HAT) catalysis. This catalytic merger allows a C-H to carbanion activation by the abstraction of a hydrog ...[more]

PMID: 32686166

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