Pyrroles and related compounds. Part XX. Syntheses of coproporphyrins

Abstract

Coproporphyrin-I has been synthesised by modifications of Fischer's original methods; Coproporphyrin-II has been synthesised by three methods including a variant of the MacDonald method, involving self-condensation of a 5-formylpyrromethane-5′-carboxylic acid. Coproporphyrins-III and -IV and a related porphyrin tricarboxylic acid have been synthesised by application of the a-oxobilane route. The products in each case were single isomerically pure species as shown by spectroscopic, chromatographic, X-ray, and m.p. comparisons with each other and with authentic samples prepared by other workers.