Han Wendan, Li Yuanhang, Raveendra Babu Kaki, Li Jing, Tang Yuhai, Wu Yong, Xu Silong
School of Chemistry and Xi'an Key Laboratory of Sustainable Energy Materials Chemistry, Xi'an Jiaotong University, Xi'an 710049, P. R. China.
J Org Chem. 2021 Jun 4;86(11):7832-7841. doi: 10.1021/acs.joc.1c00717. Epub 2021 May 17.
Herein we describe a catalyst-free regioselective [3 + 3] annulation/oxidation reaction of cyclic amidines such as DBU (1,8-diazabicyclo(5.4.0)undec-7-ene) and DBN (1,5-diazabicyclo(4.3.0)non-5-ene) with activated olefins, ., 2-arylidenemalononitriles and 2-cyano-3-aryl acrylates, to afford tricyclic 2-pyridones and pyridin-2(1)-imines, respectively. The mechanism has been proposed based on DFT calculations. In the reaction, the cyclic amidines serve as -bisnucleophiles for the cyclization, while the olefins play a dual role by acting as both reactants and oxidants.
