Highly regio- and stereoselective synthesis of alkylidenecyclopropanes via Ru(II)-Pheox catalyzed asymmetric inter- and intramolecular cyclopropanation of allenes.

An efficient protocol for the synthesis of optically active alkylidenecyclopropanes (ACPs) via the Ru(II)-Pheox catalyzed asymmetric cyclopropanation of allenes has been established. This catalytic system proceeded with high regioselectivity to give the ACP products in high yield with high diastereoselectivity (up to 99/1) and enantioselectivity (up to 99% ee).