Copper-Facilitated Suzuki Reactions: Application to 2-Heterocyclic Boronates

The palladium-catalyzed Suzuki−Miyaura reaction has been utilized as one of the most powerful methods for C−C bond formation. However, Suzuki reactions of electron-deficient 2-heterocyclic boronates generally give low conversions and remain challenging. The successful copper(I) facilitated Suzuki coupling of 2-heterocyclic boronates that is broad in scope is reported. Use of this methodology affords greatly enhanced yields of these notoriously difficult couplings. Furthermore, mechanistic investigations suggest a possible role of copper in the catalytic cycle.