Solvent-free and one-pot Biginelli synthesis of 3,4-dihydropyrimidin-2(1H)-ones and 3,4-dihydropyrimidin-2(1H)-thiones using ionic liquid N,N-diethyl-N-sulfoethanammonium chloride {[Et3N–SO3H]Cl} as a green catalyst.

In this work, the ionic liquid triethylamine-bonded sulfonic acid {[Et3N–SO3H]Cl}, N,N-diethyl-N-sulfoethanammonium chloride was used as a green acidic homogeneous catalyst to synthesis of 3,4-dihydropyrimidin-2(1H)-ones and 3,4-dihydropyrimidin-2(1H)-thiones as two categories of heterocycles, from aldehyde, dicarbonyl compound and urea or thiourea throughout the one-pot three components cyclocondensation reactions. The dihidropyrimidineones and dihydropyrimidinethiones derivatives that synthesized in this method are two important categories of heterocyclic compounds with biologic and pharmacologic activity. The ionic liquid that used in these reactions act as Bronsted acid and green homogeneous catalyst and has N-S bond in its cationic fragment and easily synthesised. The advantages of our method are solvent-free conditions, green process and high isolated yield of products.