Sonogashira cross-coupling reaction catalysed by mixed NHC-Pd-PPh3 complexes under copper free conditions

Abstract

Mixed NHC–Pd–PPh3 complexes with a methoxyethyl-substituted N-heterocyclic carbene (NHC) were synthesised and characterised by NMR, HRMS, elemental analysis and X-ray crystallography for complex 3b. These complexes were applied to Sonogashira cross-coupling reactions between aryl bromides and phenylacetylene in DMF at 80 °C. All palladium complexes were stable and showed high catalytic activity in Sonogashira reactions at low catalyst loading and ambient reaction conditions.