Three-component condensation of an aldehyde, 1,3-dicarbonyl compound and urea or thiourea proceeds smoothly at room temperature in the presence of 5 mol % of NbCl5 under extremely mild conditions to afford the corresponding 3,4-dihydropyrimidines in high to quantitative yields. This method is very useful for the synthesis of a wide range of dipyrimidinones at room temperature from aromatic, heterocyclic, and aliphatic aldehydes.
在极温和的条件下,5摩尔%NbCl5的存在下,醛、1,3-二羰基化合物和
脲或
硫脲的三组分缩合在室温下顺利进行,获得相应的3,4-二氢
嘧啶,在高至定量的产率下。这种方法非常适用于从芳香、杂环和脂肪醛室温合成广泛范围的双
嘧啶酮。