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Microporous material: an efficient and recyclable catalyst for expedite regioselective synthesis of pyrimidobenzimidazoles
1 , * 2
1  Chemistry Department, University of Rajasthan, Jaipur-302004, India
2  Indian Oil Corporation Limited, R&D Center, Faridabad-121007, India

Abstract: Microporus materials are active catalysts in regioselective synthesis of pyrimidobenzimidazoles. Five kinds of zeolites were studied and they showed quite different catalytic activities due to their wide acid sites distributions and various pore structures. Hβ zeolite was found to be the best in activity for synthesis of isomer 5 while the basic catalyst NaY zeolite found suitable for synthesis of isomers 4. The main acid sites of H-zeolites were Brönsted acid sites, and H+ was the catalytic acid site. The methodology involves a ring closure by different ways based on the reaction medium was confirmed by NOE and X-ray studies.
Keywords: Microporus materials, Zeolite, Pyrimido[1,2-a]benzimidazole, Microwave irradiation