Tetrapyrrole products from electrochemical cyclization of 1′,8′-Disubstituted-a,c-biladiene salts

Anodic oxidation of 1′,8′-dimethyl- and other 1′,8′-disubstituted a.c-biladiene salts affords novel cyclized products. In addition to porphyrin, an unconjugated macrocyclic intermediate product resulting from oxidadve cyclizatfon during porphyrin synthesis is isolated, structurally identified, and characterized with regard to its spectroscopy, electrochemical behavior and chemical reactivity. The formation of a novel homoporphyrin from a 1′-ethoxycarbonylmethy-8′-(2-methoxycarbonylethyl)-a,c-biladiene salt is also briefly discussed. © 1991