Iron(II) complexes bearing tridentate PNP pincer-type ligands as catalysts for the selective formation of 3-hydroxyacrylates from aromatic aldehydes and ethyldiazoacetate

Several new iron(II) complexes of the types [Fe(PNP)(CO)(CH3CN)(2)](2+), [Fe(PNP)(CO)(2)Br](+), and Fe(PNP)Cl-2 containing tridentate PNP pincer-type ligands have been prepared and characterized. Some of them turned out to be efficient catalysts for the coupling of aromatic aldehydes with ethyldiazoacetate (EDA) to give 3-hydroxyacrylates. These reactions are highly chemoselective, proceed under mild conditions, exhibit good scope, and circumvent the need of slow addition of EDA at low temperature.