New methodology was developed for synthesis of regiochemically pure porphyrins with D 2 h symmetry (eg 9) via tetramerization reactions involving two different pyrroles. The two pyrrole components were a 2, 5-diunsubstituted pyrrole (eg 11) and a 2, 5-bis [(N, N- dimethylamino) methyl] pyrrole (eg 10), the latter being formed from a 2, 5-di-unsubstituted pyrrole by treatment with excess Eschenmoser's reagent (N, N- ...