Regioselective C-H amination of free base porphyrins via electrogenerated pyridinium-porphyrins and stabilization of easily oxidized amino-porphyrins by protonation

Chem Commun (Camb). 2020 Jan 21;56(6):884-887. doi: 10.1039/c9cc07351e.

Abstract

Four free base aminoporphyrins were synthesized in two steps via regioselective anodic nucleophilic substitution with pyridine followed by ring opening of the electrogenerated pyridinium with piperidine. The X-ray crystallographic structure of the unstable 2-aminotetraphenylporphyrin was solved. Protonation of this latter compound leads to the stable diiminium porphyrin salt.