Electrophilic nitration of meso-tetraarylporphyrin complexes at the β-pyrrolic position

The selective nitration of meso-tetraphenylpoiphyrin complexes is described. The reaction of the above porphyrinates with 25% HNO3 or 5% HNO3 at room temperature or 0-5 degrees C, respectively, results in the formation of the corresponding mono beta-nitroporphyrins (56-81%), accompanied by small amounts of a mixture of beta,beta-dinitro by-products. The results described above are the first known examples of beta-mononitration of meso-tetraarylporphyrin complexes under electrophilic conditions. Reactions with nickel(II), copper(II), and cobalt(II) porphyrinates are discussed.