Preparation of 4,7-diphenyl-1,10-phenanthroline-2,9-dicarboxylic acid catalyzed by iron(III)porphyrins with (diacetoxyiodo)benzene

Using iron(III)porphyrins in combination with (diacetoxyiodo)benzene allows for the conversion of 2,9-bis(bromomethyl)-4,7-diphenyl-1,10-phenanthroline into 4,7-diphenyl-1,10-phenanthroline-2,9-dicarboxylic acid. This method provides a cost-effective and environmentally-friendly oxidation procedure using less toxic PhI(OAc)₂ and biologically relevant iron(III)porphyrins. The catalytic activity of five kinds of iron-metallated functional porphyrins were investigated using different oxidants, including air, H₂O₂, PhI(OAc)₂, PhIO and NaClO. Our results showed that the use of T(p-NO₂)PPFeCl with PhI(OAc)₂ as the oxidant in the presence of water displays remarkable activity for the desired oxidation reaction. The generality of this method was examined by synthesizing the carboxylic acids of pyridines and quinolines.