Catalytic Asymmetric Cyclopropanation of 1,1-Disubstituted Electron-Deficient Alkenes with Dimethyl Diazomalonate

The catalytic asymmetric synthesis of enantioenriched 1,1-cyclopropane diesters is reported. A reaction combining Rh2(R-p-BTPCP)4 as the chiral catalyst, dimethyl diazomalonate, and 1,1-disubstituted electron-poor alkenes was developed, providing access to a broad range of tetrasubstituted enantioenriched cyclopropanes. The reaction proceeded smoothly, and the products were isolated in moderate to good yields with good to excellent enantioselectivities.