The chemistry of pyrrolic compounds. XLVII. The synthesis of a possible biogenetic precursor of haem a and its relationship to the prosthetic group ofmyeloperoxidase and to cryptoporphyrin a

Abstract

The synthesis of 18-demethyl-18-formylprotoporphyrin dimethyl ester is described and the role of this compound as an intermediate in the biosynthesis of haem a is considered. A possible relationship between a compound of this structure and the prosthetic group of myeloperoxidase is discussed. The cryptoporphyrin a fraction of ox heart extracts has been reexamined and shown to consist of a mixture of Spirographis porphyrin and its isomer which presumably arise from the in vitro oxidation of the vinyl groups in protoporphyrin.