A microwave assisted three-component condensation of β-keto ester, aldehydes, and urea or thio-urea catalysed by TTSA to a biologically active 3,4-dihydropyrimidin-2(1H)-ones is described. The reactions were completed in short time, simple work up procedure, and the catalyst could be recovered by mere filtration and recycled for five consecutive runs without significant loss of activity.