Synthetic studies relevant to biosynthetic research on vitamin B12. Part 2. Syntheses of C-methylated chlorins via lactams

Abstract

C-Methylated chlorins have been synthesised by two approaches. For one, ring-B and ring-C of the final chlorin were built sequentially onto a thiolactam system which acted as the A-D component. The preferred alternative method involved joining together a lactam (a dihydropyrromethenone) as A-D precursor with a pyrromethane as the B-C component, the final ring-closure to the chlorin being carried out on a Cu^II template.