We have presented the synthesis of some 3,4-dihydro- pyrimidinones using quaternary ammonium salts in aque- ous sodium hydroxide. The yield of Biginelli product increased according to the size of the cation of the qua- ternary ammonium salt. The use of quaternary ammo- nium salt leads to an exaltation of the basicity of hy- droxide anion, which is transferred to organic phase where reaction occurs. The yield decreased in the order Cl− > Br−.