Efficient and copper-free Pd(OAc)2/DABCO-catalyzed Sonogashira cross-coupling reaction

An efficient and copper-free palladium-catalyzed Sonogashira cross-coupling reaction protocol is presented. In the presence of 3 mol% of Pd(OAc)(2) and 6 mol% of DABCO, cross-coupling of various aryl halides (iodides and bromides) with terminal alkynes afforded the corresponding alkynes in moderate to excellent yields. Moreover, high TONS (turnover numbers, up to 720 000 for the reaction of 1-iodo-4-nitrobenzene with phenylacetylene) for the Sonogashira cross-coupling reaction were observed.