title: Nucleophilic ring-opening of iron(III)-hydroxy-isoporphyrin.
abstract: The reactions of iron(III) hydroxyisoporphyrin, chloro[5-(hydroxy)-5,10,15,20-tetrakis(4-methyl)-5,21H-porphinato]iron(III) [Fe(4-Me-HTPI)(Cl)](-), 1 and chloro[5-(hydroxy)-5,10,15,20-tetrakis(4-methoxy-5,21H-porphinato]iron(III) [Fe(4-OMe-HTPI)(Cl)](-), 2 with different O(-), N(-) and S(-) nucleophiles have been performed to understand the reactivity of iron isoporphyrins with nucleophiles. The treatment of iron(III) hydroxy isoporphyrin with alcohols is found to form ring opened 19-benzoyl-1-alkoxy-bilin iron complexes. When alkyl amines were used the formation of ring opened 19-benzoyl-1-alkylamine-bilin iron complexes was observed, but heterocyclic N-nucleophiles such as pyridine and imidazole form benzoyl bilinone iron complexes. No role of oxygen was found in these nucleophilic ring opening reactions. The treatment of a S-nucleophile such as PhSH is found to reduce iron(III)-hydroxyisoporphyrin in the parent iron(III) porphyrin compound. The ring opening products were characterized using electronic and ESI-mass spectroscopy. The mechanism for the formation of ring opening products is based on the formation of a tetrahedral intermediate at the carbon atom near the saturated meso carbon atom similar to the hydrolytic pathway of verdoheme conversion to biliverdin.
authors.affiliation: Department of Chemistry, North Eastern Regional Institute of Science and Technology, Nirjuli, Arunachal Pradesh-791109, India. jnb@nerist.ac.in.
authors.forename: Jagannath
authors.initials: J
authors.lastname: Bhuyan
mesh_terms: D000438:Alcohols / Q000737:chemistry; D001664:Biliverdine / Q000737:chemistry; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry; D005290:Ferric Compounds / Q000737:chemistry*; D006418:Heme / Q000031:analogs & derivatives / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D011166:Porphyrins / Q000737:chemistry*; D011789:Quantum Theory
chemical_list: D000438:Alcohols; D056831:Coordination Complexes; D005290:Ferric Compounds; D011166:Porphyrins; C099547:verdoheme; D006418:Heme; D001664:Biliverdine