Approaches to the stepwise synthesis of benzoporphyrins and phthalocyanines. Part 2: Synthesis of a 5-azadibenzo[b,g]porphyrin from benzopyrromethene intermediates

✍ Scribed by Raymond Bonnett; Kawulia Okolo

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 93 KB
• Volume: 03
• Category: Article
• ISSN: 1088-4246
• DOI: 10.1002/(sici)1099-1409(199908/10)3:6/7<530::aid-jpp171>3.0.co;2-q

✦ Synopsis

An azadibenzoporphyrin (13,17-diethyl-12,18-dimethyl-5-azadibenzo[b,g]porphyrin, 6) is prepared by a 2 × 2 synthesis from a 1-bromobenzopyrromethene precursor by treatment with sodium azide at 140 °C in solvent. Yields depend on solvent, 35% being obtained in quinoline and 84% in DMF. Treatment of 1-bromo-8-ethyl-7,9-dimethylbenzopyrromethene hydrobromide with sodium azide at 60 °C in DMF gives the fused tetrazolo system 8 (8-ethyl-7,9-dimethyltetrazolo[1,5-i]benzopyrromethene) (X-ray structure), which appears to be, or to lead to, an intermediate in the macrocyclization at the higher temperature.