Post-synthetic methods for functionalization of imidazole-fused porphyrins

Several methods for the post-synthetic modification of imidazo[4,5-b] porphyrins are reported. First, a synthetic approach to the isomeric difunctionalized porphyrins, containing two b, b'fused 2-aryl-1H-imidazole cycles at adjacent or opposite pyrrole rings of the macrocycle is developed. The core chemistry of this synthetic route is the transformation of 2-aryl-1H-imidazo[4,5-b] porphyrins into corresponding imidazodioxochlorins followed by Debus-Radziszewski condensation with aromatic aldehyde. Next, 2-( 4-bromophenyl)-1H-imidazo[4,5-b]-5,10,15,20-tetramesitylporphyrin was transformed into useful carboxy-and phosphonato-substituted precursors for material chemistry according to palladium-catalyzed C-C and C-P bond forming reactions.