DFT study on the [4+4] domino cycloaddition of ynones with benzylidenepyrazolones to access eight-membered cyclic ethers: effects of DBU vs. Et3N†
*ab
Rongxing
He
*b
Abstract
The mechanisms of [4+4] domino cycloaddition of ynones with benzylidenepyrazolones to access highly substituted eight-membered cyclic ethers are studied to explore the effects of bases (t-BuOK vs. DBU vs. Et3N) based on DFT calculations. Our theoretical calculations indicate that the bases can promote the present catalytic reaction as the H+-shuttle agents by a two-step H+-shift reaction. More importantly, the calculations reveal that the difference in the catalytic activity of bases is primarily attributed to their electron-donating ability (t-BuO− > DBU > Et3N). The catalytic activity order of bases is t-BuO− > DBU > Et3N for the present base-catalyzed domino reactions. In a word, the present calculated results can reasonably explain the experimental phenomena and provide useful guidance and advice for the synthesis of medium-sized rings via the domino reactions to select the appropriate bases.
![Graphical abstract: DFT study on the [4+4] domino cycloaddition of ynones with benzylidenepyrazolones to access eight-membered cyclic ethers: effects of DBU vs. Et3N](/en/Image/Get?imageInfo.ImageType=GA&imageInfo.ImageIdentifier.ManuscriptID=D0NJ04280C&imageInfo.ImageIdentifier.Year=2021)
Please wait while we load your content...
