Phosphorus pentachloride (PCl5) mediated synthesis of tetraarylporphyrins

A new synthesis of porphyrins from pyrrole and substituted benzaldehydes is described, with PCl5 as catalyst. Aromatic aldehydes condense irreversibly with pyrrole in the presence of this catalyst, and aerobic oxidation of porphyrinogen provides functionalized porphyrins in yields of 20-65%.