Transformation of chlorins into bile pigment analogues

Abstract

Treatment of trans-octaethylchlorin (1) with one equivalent of thallium(III) trifluoroacetate affords the corresponding aquo-hydroxide chelate (2) after chromatography on deactivated alumina; with four equivalents of the reagent, the ring opened dihydrobiliverdin (4) is obtained. When zinc trans-octaethylchlorin is treated with one equivalent of thallium(III) trifluoroacetate, the zinc meso-trifluoroacetoxy-trans-octaethylchlorin (12) is produced; hydrolysis of the trifluoroacetoxy-function in (12) in the presence of oxygen furnishes the dihydrobiliverdin (4) in high yield.