Catalytic asymmetric cyclopropanation using copper complex of optically active bipyridine as a catalyst

Optically active 8,8′-di(trimethylsilyl)-5,5′,6,6′,7,7′,8,8′-octahydro-2,2′-biquinoline (7) was found to be an effective catalyst for enantioselective cyclopropanation of olefins. For example, the reaction of styrene and t-butyl diazoacetate in the presence of 7 proceeded with high enantioselectivity of 92% ee, to give t-butyl trans-2-phenylcyclopropanecarboxylate. On the other hand, the reaction of trans-β-methylstyrene gave the cis-isomer of >99% ee as a major product.