The mechanism of the reactions of ammonia and benzaldehyde with three different beta-dicarbonyl compounds to form the corresponding dihyropyridines has been followed by NMR. In each case the pathway is shown to involve the reaction of benzaldehyde with one molecule of beta-dicarbonyl to give chalcone, and of the ammonia with a second molecule of beta-dicarbonyl to give an enamine. The rate determining
氨和
氨与
苯甲醛与三种不同的β-二羰基化合物反应形成相应的
二氢吡啶的反应机理已通过NMR进行了追踪。在每种情况下,均显示该途径涉及
苯甲醛与一个分子的β-二羰基分子反应生成
查尔酮,而
氨与第二分子的β-二羰基分子反应生成烯胺。速率确定阶段显示为
查尔酮向烯胺的迈克尔加成。