Abstract
An efficient synthesis of 3,4-dihydropyrimidinones (DHPMs) using bismuth (III) nitrate as a catalyst for the first time from an aldehyde, β-keto ester and urea in acetonitrile is described. Compared to the classical Biginelli reaction conditions, this new method consistently has the advantage of excellent yields (80-93%) and short reaction time (1.5-2.5 hours) at room temperature.
Highlights
Dihydropyrimidinones (DHPMs) and their derivatives exhibit wide range of biological activities such as antibacterial, antiviral, antitumor and anti-inflamatory actions.[1]
We have developed a new methodology for the synthesis of DHPMs by a threecomponent condensation in one pot using a catalytic amount of Bi(NO3)[3]
By using Bi(NO3)[3] as a catalyst at ambient temperature, the yields of the one-pot Biginelli reaction can be increased from 25-55% to 56-95% while the reaction time is shortened from 18 to 1-4 h
Summary
Dihydropyrimidinones (DHPMs) and their derivatives exhibit wide range of biological activities such as antibacterial, antiviral, antitumor and anti-inflamatory actions.[1]. Biginelli (1893) reaction[5] is a simple one pot condensation of an aldehyde, ketoester and urea or thiourea in the presence of a catalytic amount of acid to produce 3,4-dihydropyrimidin-2-(1H)-ones and which often suffer from low yields, especially in the case of substituted aromatic and aliphatic aldehydes.[6] Even though high yields could be achieved by following complex multi-step procedures,[7] these methods lack the simplicity of the original one-pot Biginelli protocol. Many of these methods involve expensive reagents, stoichiometric amounts of catalysts, strongly acidic conditions, long reaction times, unsatisfactory yields and incompatibility with other functional groups.
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