Reusable and highly enantioselective water-soluble Ru(II)--Pheox catalyst for intramolecular cyclopropanation of diazo compounds.

A reusable and highly enantioselective catalyst for the intramolecular cyclopropanation of various diazo ester and Weinreb amide derivatives was developed. The reactions catalyzed by a water-soluble Ru(II)--Pheox catalyst proceeded smoothly at room temperature, affording the corresponding bicyclic cyclopropane ring-fused lactones and lactams in high yields (up to 99%) with excellent enantioselectivities (up to 99% ee). After screening of various catalysts, the Ru(II)--Pheox complex having an ammonium group proved to be crucial for the intramolecular cyclopropanation reaction in a water/ether biphasic medium.

Highly stereoselective cyclopropanation of diazo Weinreb amides catalyzed by chiral Ru(ii)-Amm-Pheox complexes.

The first highly stereoselective cyclopropanation of diazo Weinreb amides with olefins was accomplished using chiral Ru(ii)-Amm-Pheox complex to give the corresponding chiral cyclopropyl Weinreb amides in high yields (up to 99%) with excellent diastereoselectivities (up to 99 : 1 dr) and enantioselectivities (up to 96% ee).