OICC Press Iranian Journal of Catalysis 2345-4865 2 4 2024 02 03 A fast, simple and convenient procedure for the synthesis of fused pyrimidinone derivatives by using [Hmim][HSO4] as a green, efficient and reusable catalyst under solvent-free conditions EN Leila Khazdooz Laser and Biophotonics in Biotechnologies Research Center, Isfahan (Khorasgan) Branch, Islamic Azad University, Isfahan 81595-158, Iran Amin Zarei Department of Science, Fasa Branch, Islamic Azad University, PO Box No. 364, Fasa 7461713591, Fars, Iran. Abdol R. Hajipour Department of Pharmacology, University of Wisconsin, Medical School, 1300 University Avenue, Madison, 53706-1532, WI, USA. Nafisehsadat Sheikhan Department of Chemistry, Faculty of Sciences, Najafabad Branch, Islamic Azad University, Najafabad, Esfahan, P.O. Box 517, Iran. Journal Article 2024 02 03 In the present of methylimidazolium hydrogen sulfate, the synthesis of arylidene heterobicyclic pyrimidinones is studied by condensation of aromatic aldehyde, cyclopentanone, and urea or thiourea. Using solvent-free conditions, non-toxic and inexpensive materials, simple and clean work-up, short reaction times and good yields of the products are the advantages of this method.