It is proposed that the biosynthesis of uroporphyrinogen III, the parent precursor of the natural porphyrins, chlorins and corrins, involves a 2H-pyrrole (pyrrolenine) as a key intermediate. Model pyrrolenines have now been used to show that (a) pyrrolylmethylpyrrolenines readily undergo rearrangement in a way which matches that suggested in the biosynthetic proposal; (b) there is regioselectivity in the rearrangement which also parallels that required for the biosynthesis of uroporphyrinogen III. This work adds further support to the biosynthetic proposal by showing that all the required chemistry is both feasible and facile.
Department of Chemistry
University of Cambridge