Building Trisubstituted Ethylenes from Terminal Alkenes via Debrominative Ring-opening Trifluoromethylations of Geminal Dibromocyclopropanes

Abstract

CuI-catalyzed regio- and stereoselective dehalogenative ring-opening trifluoromethylations of geminal dibromo- or dichlorocyclopropanes or monobromocyclopropanes delivered stereodefined trisubstituted or disubstituted ethylenes bearing a CH2CF3 group in good yields. CuCF3 species likely promoted generation of cyclopropyl cation and its ring-opening to generate allyl radical. Purple light promoted reductive monodebromination of gem-dibromorocyclopropanes was also developed.