BIOSYNTHESIS OF PORPHYRINS AND RELATED MACROCYCLES - PART 50 - SYNTHESIS OF THE N-FORMYL-DIHYDRO ANALOG OF THE SPIRO-INTERMEDIATE AND ITS INTERACTION WITH UROPORPHYRINOGEN-III SYNTHASE

The proposed intermediacy of the spiro-system 1 for the biosynthesis o f uroporphyrinogen III has focused attention on its synthesis. In this paper the approach that is explored is to carry a dihydropyrrole thro ugh the entire synthesis with the intention of converting it into a 2H -pyrrole (pyrrolenine) in one of the final steps. The chemistry of the different types of synthetic intermediates is described and also it i s demonstrated that the N-formyl dihydropyrrole 37 is a strong inhibit or of cosynthetase. The conclusion is reached that of all the possible routes to the spiro-pyrrolenine 1, that via the protected dihydropyrr ole 30 shows the greatest promise.