Microwave-Assisted Solvent- and Cu(I)-Free Sonogashira C-C Cross-Coupling Catalysed by Pd Ionanofluids

Abstract

The microwave-assisted Sonogashira C-C cross-coupling reaction catalysed by Pd ionanofluids based on bis(trifluoromethane-sulfonyl)imide (NTf2) ionic liquids, [Cnmim][NTf2] (n = 4, 6 or 8), is described here. An organic solvent- and Cu(I)-free methodology running under very mild conditions was established by creating in situ catalysts from Pd(II) salts and [Cnmim][NTf2]. The microwave-irradiated catalytic systems quickly yielded almost quantitative conversions of 4-bromoanisole and phenylacetylene (model reaction) into the desired 1-methoxy-4-(phenylethynyl)benzene as a single product, and a good recyclability of the Pd ionanofluids.