Synthesis of Trifluoromethyl Substituted Cyclopentanes through Boron Radical-Catalyzed Cycloaddition Reaction of Trifluoromethyl Alkenes

A highly efficient protocol for synthesis of trifluoromethyl-substituted cyclopentanes, a structural motif ubiquitous in bioactive compounds and natural products, via boron radical-catalyzed (3+2) cycloaddition of aroyl cyclopropanes and trifluoromethyl substituted alkenes was developed. Employing readily available precursors, this modular, atom-economical, metal-free and operationally simple process was compatible with diverse functional groups, giving the products in generally good to high yields. Trifluoromethyl-substituted bicyclo[2.1.1]hexanes (BCHs) were analogously prepared.