General Catalytic Enantioselective Access to Monohalomethyl and Trifluoromethyl Cyclopropanes.

An efficient catalytic enantioselective access to chiral functionalized trifluoromethyl cyclopropanes from two classes of diazo compounds and α-trifluoromethyl styrenes using Rh2 ((S)-BTPCP)4 as a catalyst is described. This method provides an efficient and practical strategy for the synthesis of highly functionalized CF3 -cyclopropanes with excellent diastereoselectivities (up to 20:1) and enantioselectivities (up to 99 % ee). The depicted methodology represents, to date, the most efficient catalytic enantioselective method to access highly decorated chiral CF3 -cyclopropanes. Extension to chiral monohalomethyl cyclopropanes in high ee is also reported.