BIOSYNTHESIS OF PORPHYRINS AND RELATED MACROCYCLES - PART 47 - SYNTHESIS AND CHEMISTRY OF 2H-PYRROLES (PYRROLENINES) RELATED TO THE PROPOSED SPIRO-INTERMEDIATE FOR PORPHYRIN BIOSYNTHESIS

It is proposed that the biosynthesis of uroporphyrinogen III 3, the pa rent precursor of the natural porphyrins, chlorins and corrins, involv es a pyrrolenine 2 as a key intermediate, yet methods for the synthesi s of such systems are not available. Novel routes for the synthesis of pyrrolenines by desulfurisation of unsaturated thiolactams have now b een devised and the chemistry of such compounds has been explored. Enz ymic experiments are carried out using a model pyrrolenine indicating that deletion of one of the pyrrole rings of the putative intermediate 2 leads to loss of tight binding.