Generating Fischer-Type Rh-Carbenes with Rh-Carbynoids

We describe the first catalytic generation of Fischer-type acyloxy Rh(II)-carbenes from carboxylic acids and Rh(II)-carbynoids. This novel class of transient donor/acceptor Rh(II)-carbenes evolved through a cyclopropanation process providing access to densely functionalized cyclopropyl-fused lactones with excellent diastereoselectivity. DFT calculations allowed the analysis of the properties of Rh(II)-carbynoids and acyloxy Rh(II)-carbenes as well as the characterization of the mechanism.

Automated summary

We report the first successful generation of Fischer-type acyloxy Rh(II)-carbenes from carboxylic acids and Rh(II)-carbynoids. This novel class of transient donor/acceptor Rh(II)-carbenes evolves through a cyclopropanation process and allows access to densely functionalized cyclopropyl-fused lactones with excellent diastereoselectivity. DFT calculations were performed to analyze the properties of both Rh(II)-carbynoids and acyloxy Rh(II)-carbenes, as well as to characterize the reaction mechanism.