Active methylene compounds such as acetone, butanone, cyclopentanone, nitromethane, malononitrile, ethyl 2-cyanoacetate, diethyl malonate, and ethyl acetylacetate react with the C3 position of N-confused porphyrin in the presence of L-proline in refluxing THF–EtOH affording a variety of N-confused porphyrin derivatives in moderate yield. L-Proline catalyzes the reaction facilitating the formation of the carbanion derived from an active methylene compound simultaneously delivering protons to the N-confused porphyrin. Both processes are key factors of this reaction.
