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Learning From Vitamin B 12 ‐Mediated Reactions: Cobalt(III)−Carbon‐Assisted Catalytic C−H Difluoroacylation of (Hetero)Arenes through Controlled‐Potential Electrolysis
Author(s) -
Hossain Md. Jakir,
Ono Toshikazu,
Yano Yoshio,
Hisaeda Yoshio
Publication year - 2019
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.201900164
Subject(s) - cobalt , catalysis , chemistry , homolysis , bond cleavage , electrolysis , medicinal chemistry , aryl , alkyl , photochemistry , radical , organic chemistry , electrode , electrolyte
The synthesis of difluoromethylated (CF 2 R) (R=H, alkyl/aryl, CO 2 R, etc.) compounds has received considerable attention in recent years. In this study, the cobalt(III)−carbon‐mediated catalytic C−H difluoroacylation of unactivated arenes and heteroarenes using BrCF 2 CO 2 Et is reported. This catalytic cycle is based on a valence change of the cobalt catalyst, a naturally derived vitamin B 12 derivative, driven by controlled‐potential electrolysis at −0.8 V vs. Ag/AgCl under visible‐light irradiation in dimethyl sulfoxide. A broad substrate scope is demonstrated, and two compounds were characterized according to their X‐ray crystal structures. Mechanistic studies showed that the reaction proceeds through a radical pathway mediated by homolytic cleavage of the cobalt(III)–carbon bond. A turnover number of more than 100 was observed, owing to the inherent stability of the vitamin B 12 framework. This naturally derived catalytic system has potential applications in medicinal chemistry and materials science.