A reactant promoted solvent free synthesis of 3,4-dihydropyrimidin-2 (1H)-thione analogues using ammonium thiocyanate

This is the first-time ammonium thiocyanate (NH4SCN) has been used as a self-promoting reactant for the synthesis of 3,4-dihydropyrimidin-2(1H)-thiones. This report describes a greener, efficient and economic protocol for one pot three-component synthesis of Biginelli compounds using various aldehydes, beta-ketoesters and ammonium thiocyanate. Ammonium thiocyanate being a weak acid, accelerate the rate of reaction to obtain Biginelli compounds in solvent-free condition at 110 degrees C. The key advantages of the present method are high yields, short reaction time, solvent free condition, easy workup and ability to tolerate a variety of functional groups. Ammonium thiocyanate is readily available, cheaper, safer and industrial acceptable material which gives economical as well as ecological rewards to the present method. (C) 2017 Elsevier Ltd. All rights reserved.