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.