PPh3-catalyzed [2 + 2 + 2] and [4 + 2] annulations: synthesis of highly substituted 1,2-dihydropyridines (DHPs).
PPh(3)-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, PPh(3)-catalyzed [4 + 2] annulations have also been discovered.
Liu
Huimin
H
Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, Shanghai 200237, China.
Zhang
Qiongmei
Q
Wang
Limin
L
Tong
Xiaofeng
X