Approaches to the stepwise synthesis of benzoporphyrins and phthalocyanines .1. Synthesis of opp-dibenzoporphyrins (dibenzo[g,q]porphyrins)

A stepwise synthesis of the opp-dibenzoporphyrin (dibenzo[g,q] porphyrin) system involving isoindole precursors is described. 3-Halogeno-1-formylisoindoles are condensed with various a-unsubstituted pyrroles to give the corresponding benzopyrromethene hydrobromides, Thermal self-condensation of such compounds bearing an a-methyl group gives the corresponding opp-dibenzoporphyrin derivatives in low to modest yields depending on the B-substitution pattern of the original pyrrole component.