Novel and improved syntheses of 5,15-diphenylporphyrin and its dipyrrolic precursors

✍ Scribed by Christian Brückner; Jeff J. Posakony; Claire K. Johnson; Ross W. Boyle; Brian R. James; David Dolphin

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 134 KB
• Volume: 02
• Category: Article
• ISSN: 1088-4246
• DOI: 10.1002/(sici)1099-1409(199811/12)2:6<455::aid-jpp67>3.0.co;2-c

✦ Synopsis

Optimized syntheses of 5,15-diphenylporphyrin (DPP, 1) and its dipyrrolic precursors are described. A novel procedure for the synthesis of dipyrromethane (2), prepared by hydrodesulfurization of the corresponding di-2-pyrrolylthione (8), is presented, as well as an improved method to isolate large quantities of 5-phenyldipyrromethane (4), prepared by the acid-catalysed condensation of pyrrole with benzaldehyde. These dipyrromethanes are key reagents in two high-yield ( )-type syntheses of DPP. 5-Phenyldipyrromethane was formylated to provide 1-formyl-( ) and 1,9-diformyl-5-phenyldipyrromethane ( ), and reduction of 11 provided the corresponding hydroxymethyl compound 13. These compounds (11-13), however, were much less efficient precursors to DPP. Two polypyrrolic compounds, 1,1,2,2-dipyrrolylethane (9) and 5,10diphenyltripyrrane (10), potentially useful for the synthesis of porphyrinic macrocycles, were isolated as sideproducts during the dipyrromethane and 5-phenyldipyrromethane syntheses.