Direct β-amination reaction in porphyrin systems—a simple route to compounds containing two nitrogen substituents at both β-positions of the same pyrrole unit

The direct β-amination of porphyrin derivatives is described. 2-Nitro-meso-tetraarylporphyrins (zinc and copper complexes) react with N,N,N-trimethylhydrazinium iodide (TMHI) in the presence of a base (KOH/DMSO system, ca 70–80 °C) to give products of nucleophilic aromatic substitution of hydrogen. In this process, the nucleophilic replacement of a H-atom by an NH2 group takes place. The products obtained, bearing two neighbouring nitrogen substituents on the same pyrrole ring, are valuable intermediates for various synthetic uses.