Cyclopropanation was performed using the Furukawa procedure with CH 2 I 2/Et 2 Zn and α, β-unsaturated ketones. The reaction was performed in the presence of a copper salt. The reactivity was highly dependent on the substrate structure, and cyclopropanated products were obtained in better yields than those achieved using the original Simmons–Smith conditions with a Zn–Cu couple in some cases. Stereospecificity was observed in a ...