Biosynthesis of porphyrins and related macrocycles. Part IV. Syntheses of isomeric aminomethylpyrromethanes for biosynthetic study

Abstract

The aminomethylpyrromethanes (6) and (7) were required for biosynthetic studies on haem, protoporphyrin-IX and vitamin B₁₂; rational syntheses of both from methyl (1,4,5,6,7,8-hexahydro-6-oxopyrrolo[2,3-c]azepin-3-yl)-acetate (10) are described. A key stage in the synthesis of the lactam (10) is the ring closure of the amino-ester (26) catalysed by 2-pyridone. The pyrromethane lactams (8) and (9), derived by several stages from the lactam (10) were hydrolysed to yield the required aminomethylpyrromethanes, which were characterised by n.m.r. spectroscopy.