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)(CH 3 CN) 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.