Synthesis of corrins and related macrocycles based on pyrrolic intermediates.
Intermediate in structure between porphyrins and corrins are the corroles and 1-methyltetradehydrocorrins. These ring systems, like the porphyrins, can be obtained by cyclization of linear tetrapyrrolic compounds, reactions which have been shown to proceed by orbital symmetry-allowed electrocyclic processes, and examples will be quoted. Thermolysis of nickel 1-methyltetradehydrocorrins causes a migration of the methyl group whereas similar treatment of nickel 1,19-dimethyltetradehydrocorrin salts yields porphyrin derivatives; the mechanisms of these transformations have been elucidated. Stepwise hydrogenation of metal tetradehydrocorrin salts (10 double bonds) yields a series of macrocycles containing 9, 8, 7, 6 and 5 double bonds and conditions necessary to obtain corrins have been established.
D055598:Chemical Phenomena; D002621:Chemistry; D008670:Metals; D010860:Pigments, Biological / Q000138:chemical synthesis*; D011166:Porphyrins / Q000138:chemical synthesis; D011758:Pyrroles; D014805:Vitamin B 12 / Q000138:chemical synthesis
D008670:Metals; D010860:Pigments, Biological; D011166:Porphyrins; D011758:Pyrroles; D014805:Vitamin B 12