Simple and Efficient Method for One Pot Multicomponent Synthesis of 3,4-Dihydropyrimidin-2-(1H)-One Derivatives Catalyzed by Organocatalyst: Benzoic Acid

The Biginelli reaction is one the useful multicomponent reactions and a very appropriate reaction for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones derivatives. These 3,4-dihydropyrimidin-2(1H)-ones have biological and pharmacological properties which makes them a very important class of medicinal chemistry. Although they are an important class of medicinal chemistry, the syntheses of these compounds have been catalyzed by large number of strong Bronsted acids and Lewis acids under thermal conditions. Small organic molecules, organocatalysts, have been used as catalysts for the Biginelli reaction in a small number as compared to Bronsted acids and Lewis acid. Benzoic acid, which is a small organic molecule, although an acid, has never been tested for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones. Benzoic acid is an inexpensive, non-toxic molecule, it has been successfully tested here as a catalyst for the one-pot three component synthesis of 3,4-dihydropyrimidin-2-(1H)-one derivatives via Biginelli reaction between β-keto ester, a variety of aromatic aldehydes and urea or thiourea under thermal conditions using 20 mol% benzoic acid in acetonitrile solvent refluxed for 12 h to give good to high yields. This synthetic method includes inexpensive, non-toxic, easily available benzoic acid as a catalyst and is carried out in a simple operational procedure.