Synthesis and reactions of meso-(p-nitrophenyl)porphyrins

An improved methodology is reported for the regioselective nitration of the phenyl groups of meso-tetraphenylporphyrin , using NaNO2 and TFA. The degree of nitration is easily controlled by the equivalent amount of NaNO2 used and the reaction time. The nitroporphyrins are reduced to the corresponding aminoporphyrins under standard SnCl2/HCl conditions. Reaction of tri-aminoporphyrin with 1-formyl-o-carborane followed by reduction using NaBH4 gave a novel tri-carboranylporphyrin bearing amine linkages between the porphyrin and the carborane groups.