Polyphosphoric acid<span style="font-size:11.0pt;mso-bidi-font-family:"Times New Roman"; letter-spacing:.4pt" lang="EN-US"> catalyst for the one-pot synthesis of 3,4-dihydropyrimidin-2(1<i>H</i>)-ones by grinding under solvent-free conditions </span>

139-1413,4-Dihydropyrimidin-2-(1H)-ones have been obtained, in high yield, by grinding ternary mixture of different substituted aromatic aldehydes, ethyl acetoacetate and urea, in the presence of polyphosphoric acid, under solventless conditions. The facile reaction condition, simple isolation and purification procedures of this method make it a good option for the synthesis of dihydropyrimidinones.