Biosynthesis of porphyrins and related macrocycles. Part 12. Vitamin B12: studies with 1-methylbilanes

Abstract

The search for intermediates which closely follow uro'gen-III(2) on the biosynthetic pathway to vitamin B₁₂(1) has involved studies with 1-methylbilanes. Four such bilanes, ¹⁴C-labelled at the C-1 methyl group, have been synthesised by rational methods and tested as precursors of the corrin macrocycle [e.g.(4)] using an enzyme system from Propionibacterium shermanii. None of the bilanes was incorporated into (4) and this outcome is in full agreement with more recent studies.