Regioselective Halogenation and Palladium-Catalysed Couplings on 5,15-Diphenylporphyrins.
Shanmugathasan, Sakthi,; Johnson, Claire K.; Edwards Christine; Matthews Keith; Dolphin David and Boyle, Ross.
5,15-Diphenylporphyrin was regiospecifically halogenated in high yield to give 5-iodo-15-bromo-10,20-diphenylporphyrin, which was then subjected to Heck and Stille-type coupling reactions to form unsymmetrically substituted porphyrins. The regioselectivity of the iodination of 5,15-bis(3,4,5-trimethoxyphenyl)porphyrin and subsequent formation of amphiphilic porphyrins via Pd-based methodol. was also studied. The utility of this method for the synthesis of photodynamic sensitizers was demonstrated on AR4-2J rat pancreatic carcinoma cells. An inverse relationship between photodynamic activity and alkyl chain length is observed.