An efficient protocol for copper- and amine-free Sonogashira reactions catalyzed by mononuclear palladacycle complexes containing bidentate phosphine ligands

• New classes of homogenous catalysts for the Sonogashira reactions were used.
• The reactions carried out under aerobic and copper- and amine-free conditions.
• Easy preparation and low Pd loading make them ideal complexes for this reaction.
• Proposed catalytic cycle for copper-free Sonogashira reaction is presented.

An efficient protocol for copper- and amine-free Sonogashira coupling of aryl halides with phenylacetylene in mild reaction conditions under air is reported using moisture/air-stable and robust palladacycle phosphine complexes as catalyst precursors. The use of 0.001 mol% catalysts in the presence of Cs2CO3 allows the coupling reaction to proceed with moderate to good yields. Also, 31P NMR studies showed that palladacycle 1 can be reduced to zerovalent palladium in methanol, by forming dppe dioxide.

An efficient protocol copper- and amine-free palladium-catalyzed Sonogashira reaction of various aryl halides with phenylacetylene in mild reaction condition has been developed. Various aryl halides were coupled with phenylacetylene under air in the presence of 0.001 mol% of the moisture-stable and homogeneous catalysts to afford corresponding C–C products in moderate to good yields. 31P NMR studies showed that palladacycle 1 can be reduced to zerovalent palladium in methanol, by forming dppe dioxide.Figure optionsDownload as PowerPoint slide