THE EFFICIENT SYNTHESIS OF 3,4-DIHYDROPYRIMIDIN-2-(1H)-ONES AND THEIR SULFUR DERIVATIVES WITH H2SO4 IMMOBILIZED ON ACTIVATED CHARCOAL

Various 3,4-dihydropyrimidin-2-(1H)-ones (DHPMs) and their sulfur derivatives were efficiently synthesized by a one-pot cyclocondensation reaction of aromatic and aliphatic aldehydes, beta-dicarbonyl compounds and urea (or thiourea) in the presence of sulfuric acid immobilized on activated charcoal (133% w/w). The reactions were carried out in refluxing n-hexane-acetonitrile (2.5:0.5 mL) within 5-150 min to give 3,4-dihydropyrimidinones (or thiones) in high to excellent yields (81-97%).