PPh3-catalyzed [2 + 2 + 2] annulations between two units of an activated terminal alkyne and one unit of an aryl N-tosylimine have been developed to provide a synthetic method for highly substituted dihydropyridines. On the basis of the mechanism of the [2 + 2 + 2] annulation, PPh3-catalyzed [4 + 2] annulations have also been discovered.
在 PPh3 催化下,活化的末端
炔烃的两个单元与芳基 N-
对甲苯磺酸亚胺的一个单元发生了[2 + 2 + 2]环化反应,为高取代的二氢
吡啶类化合物提供了一种合成方法。在[2 + 2 + 2]环化机理的基础上,还发现了 PPh3 催化的[4 + 2]环化。