A convenient procedure for moderate-scale Rothemund synthesis of lipophilic porphyrins: an alternative to the Adler-Longo and Lindsey methodologies

Rothemund synthesis of porphyrins is conveniently achieved using p-toluenes ulfonic acid-catalysed reaction between pyrrole and aldehyde with azeotropi c removal of the water formed in the reaction. These conditions are suitabl e for moderate-scale reactions and involve an easy work-up. In this way, 5, 10,15,20-tetraheptylporphyrin (2), 5,10,15,20-tetrakis(3,5-di-tert-butylphe nyl)porphyrin (3), 5,10,15,20-tetra-tert-butylporphyrin (4) and 5,10,15,20- [pyromellitoyl(tetrakis-o-oxyethoxyphenyl)]porphyrin (5) were prepared in m oderate to good yields. (C) 1998 John Wiley & Sons, Ltd.