Diammonium Hydrogen Phosphate: a Versatile and Inexpensive Reagent for One-Pot Synthesis of Dihydropyrimidinones, Quinazolinones and Azalactones under Solvent-Free Conditions

P. Salehi^a,*, M. Dabiri^b, A.R. Khosropour ^c and P. Roozbehniya^b

^aDepartment of Phytochemistry, Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, Evin, P.O.Box 19835-389, Tehran, Iran

^bDepartment of Chemistry, Faculty of Science, Shahid Beheshti University, Evin, Tehran, 1983963113, Iran

^cDepartment of Chemistry, Faculty of Science, Razi University, Kermanshah, 67149, Iran

(Received 2 January 2006, Accepted 3 February 2006)

     Diammonium hydrogen phosphate, (NH₄)₂HPO₄, efficiently catalyzes the three-component Biginelli reaction between an aldehyde, a â-dicarbonyl compound and urea or thiourea under solvent-free conditions to afford the corresponding dihydropyrimidinones in high yields. Also, the synthesis of 2,3-disubsitituted-(3H)-quinazolin-4-ones is achieved by the one-pot reaction of isatoic anhydride, primary amines and orthoesters in the presence of (NH₄)₂HPO₄. The reaction of hippuric acid with aromatic aldehydes and acetic anhydride resulted in the formation of azalactones using catalytic amounts of (NH₄)₂HPO₄.

Keywords: Diammonium hydrogen phosphate, Solid phase, Biginelli reaction, Dihydropyrimidinones, Quinazolinones, Azalactones