Copper-free Sonogashira reactions catalyzed by a palladium(II) complex bearing pyrenealdehyde thiosemicarbazonate under ambient conditions

Abstract

Convenient synthesis of a new square-planar mononuclear palladium(II) complex bearing N,S-donor 1-pyrenaldehyde 4-methyl-3-thiosemicarbazonate (L-) as ligand is described. The identity of the complex has been established as [Pd(L)Cl(PPh3)] by elemental analysis, ESI-MS, FT-IR, NMR and single crystal X-ray crystallographic measurements. The complex has been found to be an active and efficient homogeneous catalyst for the copper free Sonogashira coupling reactions of phenylacetylene with various aryl halides (bromides and chlorides) at room temperature under aerobic conditions.