The chemistry of pyrrolic compounds. XLIII. Synthesis of the fifteen isomers of protoporphyrin

Abstract

Within the limitation that porphyrin biogenesis involves the condensation of four porphobilinogen molecules it is possible to generate fifteen isomers of protoporphyrin. All these isomers have now been constructed by ring synthesis and some comparative data obtained concerning their spectroscopic and chromatographic properties. It has been possible to make reasonable assignments for the methine protons in trifluoroacetic acid and chloroform for all the protoporphyrin isomers.