Synthesis of calixpyrroles and porphyrins over molecular sieve catalysts

The macrocyclization reaction of calix(4)pyrroles and porphyrins prepared by zeolite catalyzed synthesis in liquid phase under microwave irradiation conditions was subsequently optimized for quantitative yields. The reactions are carried out with different zeolite catalysts such as HZSM-5, HY and mesoporous Al-MCM-41 molecular sieves and the reactions are monitored by HPTLC for performance evaluation of the catalysts. The present method to synthesize macrocycles, using molecular sieves, such as solid acid catalysts in heterogeneous system, was selective and quantitative. Al-MCM-41 (pore diameter more than 20 Angstrom) performs better as to facilitate good selectivity towards quantitative yield and demonstrated excellent conversions when compared to other catalysts. (C) 2004 Elsevier B.V. All rights reserved.