Catalytic Olefin Cyclopropanation with In Situ-Generated Dialkyl Diazomethanes via Co(II)-Based Metalloradical Catalysis

The synthesis of dialkyl-substituted cyclopropanes is an important challenge in synthesis with applications in drug discovery and agrochemistry. Herein, we report on the synthesis of gem-dialkyl cyclopropanes with in situ-generated dialkyl diazo compounds under Bamford–Stevens conditions. A simple cobalt catalyst was identified to be optimal to achieve high yields. Experimental and computational studies suggest the participation of a metalloradical reaction mechanism that facilitates the carbene transfer reactions and provides access to dialkyl-substituted cyclopropanes in a single step.