Theoretical studies on the mechanism of Rh−catalyzed [3+2+1] cycloaddition reaction of vinylidene cyclopropane with carbon monoxide

Abstract

DFT calculations have been carried out to study the mechanism of the Rh-catalyzed Pauson-Khand [3+2+1] cycloaddition reaction of vinylidene cyclopropane with carbon monoxide, as well as the diastereoselectivity of the products. It is found that reaction initializes by oxidative addition involves the distal C−C bond cleavage of cyclopropane groups, which is promoted by Rh(I) complex, to give η⁴-TMM Rh(III) intermediate, followed by CO insertion. Continuing with the next process, olefin insertion, determines the formation of the cis-product or trans-product, depending on the orientation of coordinated olefin moiety to the Rh center. The calculations provide a successful interpretation of the experimental observersed diastereoselectivity.