Synthesis of oxophlorins (oxyporphyrins) from magnesium and zinc porphyrin chelates

Abstract

Treatment of magnesium or zinc porphyrins with thallium(III) trifluoroacetate, followed by an acidic work-up affords oxophlorins in high yield. The oxophlorin oxygen atom is shown to be trifluoroacetate-derived by the isolation of meso-trifluoroacetoxyporphyrins as stable intermediates; a radical mechanism is suggested for this transformation. Similar results are obtained when lead(IV) or mercury(II) trifluoroacetates are used as the oxidants, but the yields of oxophlorin are lower.