Development of porphyrin syntheses

Hans Fischer (Munich, Germany) and S. Fergus MacDonald (Ottawa, Canada) devised efficient porphyrin syntheses based on condensation reactions of dipyrromethenes (Fischer) or dipyrromethanes (MacDonald). These historically significant processes and subsequent developments are discussed, along with monopyrrole tetramerizations that give 5,10,15,20-tetra-arylporphyrins, to show that the art of porphyrin synthesis continues to flourish. Personal historical comments relating to the advancement of porphyrin syntheses using monopyrroles, dipyrroles, and open-chain tetrapyrroles are presented.