Work

Photocarboxylation of Benzylic C–H Bonds

Year: 2019

Type: article

Abstract: The carboxylation of sp3-hybridized C–H bonds with CO2 is a challenging transformation. Herein, we report a visible-light-mediated carboxylation of benzylic C–H bonds with CO2 into 2-arylpropionic acids under metal-free conditions. Photo-oxidized triisopropylsilanethiol was used as the hydrogen atom transfer catalyst to afford a benzylic radical that accepts an electron from the reduced form of 2,3,4,6-tetra(9H-carbazol-9-yl)-5-(1-phenylethyl)benzonitrile generated in situ. The resulting benzylic carbanion reacts with CO2 to generate the corresponding carboxylic acid after protonation. The reaction proceeded without the addition of any sacrificial electron donor, electron acceptor or stoichiometric additives. Moderate to good yields of the desired products were obtained in a broad substrate scope. Several drugs were successfully synthesized using the novel strategy.

Source: Journal of the American Chemical Society

DOI: 10.1021/jacs.9b05360

Authors: Qing-Yuan Meng, Tobias E. Schirmer, Anna Lucia Berger, Karsten Donabauer, Burkhard König

Institution: University of Regensburg

Language: English

Topic: Radical Photochemical Reactions

Subfield: Organic Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $5,000

Funders: Deutsche Forschungsgemeinschaft, H2020 European Research Council