The Chemistry of Pyrrolic Compounds. LXII. The Oxidative Cyclization of Bilenes-b: Identification of the Expelled Carbon Fragment

Abstract

Oxidative cyclization of the 1,19-dibenzylbilene-b salt (12) with copper(II) acetate in acetic acid/methanol yielded the expected meso-phenylporphyrin (13). Careful examination of the by-products by g.l.c./m.s , revealed the presence of benzyl acetate, indicating the fragment excluded was lost at the alcohol oxidation level. When trifluoroacetic acid was present in the cyclization mixture benzyl trifluoroacetate was the only fragment identified. Heating the meso-phenylporphyrin (13) yielded the cyclic ketonic porphyrin derivative (14).