A one-pot three component Biginelli condensation of different substituted aromatic and aliphatic aldehydes with ethyl acetoacetate and urea to the respective 3,4-dihydropyrimidin-2-(1H)-ones under solvent-free conditions that is simple, effective, and environmentally friendly was shown. Ammonium dihydrogen phosphate (NH4H2PO4) was used as a non-toxic, inexpensive, and easily available catalyst. The facile reaction condition and simple isolation and purification procedures of this method make it a good option for the synthesis of dihydropyrimidinones.
