Transition-Metal-Free Synthesis of Tertiary Aminocyclopropanes.

A transition-metal-free methodology for the construction of pharmaceutically relevant tertiary aminocyclopropanes is reported. Hydrazonamides, safe and stable carbene precursors, undergo smooth cyclopropanation with vinyl arenes in the presence of a base. The reaction proceeds with stereoselectivity to favor the Z isomer and provides facile access to a variety of substitution patterns through variation of the coupling partners.