Ru(II)-Pheox-Catalyzed Asymmetric Intramolecular Cyclopropanation of Electron-Deficient Olefins.

The first highly enantioselective intramolecular cyclopropanation of electron-deficient olefins, in the presence of Ru(II)--Pheox catalyst, is reported. The corresponding cyclopropane-fused γ-lactones were obtained in high yields (up to 99%) with excellent enantioselectivities (ee up to 99%). Moreover, this method enables efficient access to enantioenriched dicarbonyl cyclopropane derivatives, which are important intermediates for the synthesis of various bioactive compounds.