Cobalt-Catalyzed Intramolecular Hydroacylation Involving Cyclopropane Cleavage

A simple cobalt-diphosphine catalyst has been found to efficiently promote intramolecular cyclization ofortho-cyclopropylvinyl- and cyclopropylidenemethyl-substituted benzaldehydes into benzocyclooctadienone and benzocycloheptadienone derivatives, respectively. This ring-opening hydroacylation likely involves aldehyde C-H oxidative addition, olefin insertion, cyclopropane cleavage by beta-carbon elimination, and C-C bond-forming reductive elimination, as was supported by mechanistic experiments and DFT calculations.