Bismuth oxide perchlorate catalysed efficient synthesis of 3,4-dihydropyrimidin-2(1<i style="">H</i>)-ones: An improved high yielding protocol for the Biginelli reaction

Abstract

Dihydropyrimidines are prepared by a one-pot cyclo­con­densation of aldehydes, β-ketoesters and urea in acetonitrile by using bismuth oxide perchlorate as the catalyst for the first time is described. Compared to the classical Biginelli reaction conditions, this new method consistently has the advantage of excellent yields (85-95%) and short reaction time (2-4 hr) at lower temperature (40-50^oC).