Electrooxidative Rhodium-Catalyzed [5 + 2] Annulations via C-H/O-H Activations.

Electrooxidative Rhodium-Catalyzed [5 + 2] Annulations via C-H/O-H Activations.
Angew Chem Int Ed Engl. 2021 Jan 20;:
Authors: Wang Y, Oliveira JCA, Lin Z, Ackermann L
Abstract
Electrooxidative annulations involving mild transition metal-catalyzed C-H activation have emerged as transformative strategy for the rapid construction of five- and six-membered heterocycles. In contract, we herein describe the first electrochemical metal-catalyzed [5 + 2] cycloadditions to assemble valuable seven-membered benzoxepine skeletons by C-H/O-H activation. The efficient alkyne annulation featured ample substrate scope, using electricity as the only oxidant. Mechanistic studies provided strong support for a rhodium(III/I) regime, involving a benzoxepine coordinated rhodium(I) sandwich complex as the catalyst resting state, which was re-oxidized to rhodium(III) by anodic oxidation.
PMID: 33471952 [PubMed - as supplied by publisher]

Source: Angewandte Chemie - January 20, 2021 Category: Chemistry Authors: Wang Y, Oliveira JCA, Lin Z, Ackermann L Tags: Angew Chem Int Ed Engl Source Type: research