Synthesis, Reactivity, and Catalytic Applications of Isolable (NHC)Cu(CHF2) Complexes

Difluoromethyl copper complexes have been proposed as key intermediates in a variety of Cu-catalyzed difluoromethylation reactions. However, studies of these putative intermediates have been impeded by the low stability of these [Cu(CHF2)] species. This report describes the synthesis of isolable N-heterocyclic carbene ligated copper(I) difluoromethyl complexes. The stoichiometric reactions of these complexes with aryl electrophiles (i.e., diaryliodonium salts, aryl iodides, and aryl bromides) are described. In addition, N-heterocyclic carbene copper(I) species are demonstrated to serve as catalysts for the cross-coupling of aryl iodides with (difluoromethyl)trimethylsilane to afford difluoromethyl arene products.