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

A highly efficient protocol for the synthesis of trifluoromethyl-substituted cyclopentanes, a structural motif ubiquitous in bioactive compounds and natural products, via boron-radical-catalyzed (3+2) cycloaddition of aroylcyclopropanes 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.