Palladium(II) phosphine–ylide complexes as highly efficient pre-catalysts in additive- and amine-free Sonogashira coupling reactions performed under aerobic and low Pd loading conditions

Moisture and air-stable, robust palladacycle phosphine–ylide complexes as catalyst precursors were used in additive- and amine-free Sonogashira cross-coupling reactions. Various aryl halides were coupled with phenylacetylene in DMF, under air, in the presence of 0.001 mol % of the catalyst to afford the corresponding cross-coupled products in good to excellent yields. Application of the five-membered palladacycle [(P^C)PdCl2] (C1) in Sonogashira coupling reaction produced comparable catalytic activities of the seven-membered [(C^C)PdCl2] (C2) analogs.