Chemical Oxidation of Synthetic Iron(III)-Complex of 15-Phenyl Protoporphyrin IX

Abstract

Oxidative cleavage of 15-phenyl protohemin IX in pyridine solution in the presence of ascorbic acid (coupled oxidation), followed by esterification of the products with boron trifluoride-methanol rendered only three isomeric biliverdins. These were identified by 1 H NMR and MS spectrometry as 10-phenyl biliverdin IXa (1), 5-phenyl biliverdin IXβ (2) and 15-phenyl biliverdin IX8 (3) dimethyl esters. The fact that biliverdin IXy dimethyl ester derivative is not obtained indicates that oxidation fails to occur in the γ-meso-carbon bearing the phenyl group.