Synthesis, reactivity, and catalytic applications of isolable (NHC)Cu(CHF2) complexes

Abstract

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, Nheterocyclic 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.