Copper-Catalyzed 1,6-Hydrodifluoroacetylation of para-Quinone Methides at Ambient Temperature with Bis(pinacolato)diboron as Reductant

An original and efficient copper-catalyzed 1,6-hydrodifluoroacetylation of para-quinone methides with difluoroalkyl bromides has been described with bis(pinacolato) diboron (B(2)pin(2)) as reductant. In this reaction, a new C(sp(3))-CF2 bond is constructed under smart conditions. A broad substrate scope of para-quinone methides (p-QMs) make this protocol very practical and attractive. Preliminary mechanistic studies manifested that a difluoroalkyl radical pathway was involved in this reaction. Also the presence of the diboron reagent was an essential requisite in this transformation.