Phosphine-free Sonogashira coupling: reactions of aryl halides catalysed by palladium(II) complexes of azetidine-derived polyamines under mild conditions

Readily synthesised, water-stable pyridylazetidine-based Pd(II) complexes have been studied as catalysts for the Sonogashira coupling reaction. Under low catalyst loadings, various aryl bromides and chlorides were efficiently coupled with phenylacetylene at only moderately elevated temperatures (50-70 °C) and, in some cases, even at room temperature. Not only was the catalysis efficient under mild conditions but it was also operative in aerated, partly aqueous and phosphine-free media.