Palladium and copper complexes with oxygen–nitrogen mixed donors as efficient catalysts for the Heck reaction

A simple bidentate ligand, 2-(2′-hydroxyphenyl)-5,6-dihydro-1,3-oxazine, was readily prepared with a two-step synthesis. Two novel complexes of Pd(II) and Cu(II) with this (N,O) oxazine ligand have been prepared and the molecular structures of these complexes have been confirmed by X-ray structure analysis, NMR, IR and UV–Vis spectroscopy. These complexes efficiently catalyze the Heck reaction of aryl halides with olefins at 120 °C in 8 h. The reaction conditions for the Heck coupling of iodobenzene with styrene was optimized by varying the amount of the catalyst, reaction temperature, solvent and exogenous base.

Graphical abstractTwo novel complexes of Pd(II) and Cu(II) with a simple bidentate ligand, 2-(2′-hydroxyphenyl)-5,6-dihydro-1,3-oxazine have been prepared and the catalytic behavior of these two complexes was investigated in the Heck reaction.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Synthesis of palladium and copper complexes with oxazine ligand. ► Crystal structure determination of the complexes. ► Application of the complexes as efficient catalysts for the Heck reaction.