1-Methylimidazolium hydrogen sulfate/chlorotrimethylsilane: An effective catalytic system for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones and hydroquinazoline-2,5-diones

► Brønsted acidic ionic liquid, 1-methylimidazolium hydrogen sulfate, has been used as a catalyst and solvent. ► One-pot three-component synthesis of 3,4-dihydropyrimidin-2(1H)-ones was reported. ► One-pot three-component synthesis of hydroquinazoline-2,5-diones was described. ► Biginelli reactions were carried out under thermal and solvent-free conditions in high yields and a few minute. ► The ionic liquid was recovered and reused for three cycles without any loss of activities.