Organocatalytic stereoselective conjugate addition of 3-substituted oxindoles with in situ generated ortho-quinone methides
作者:Weihong Liang、Wenhao Yin、Tingzhong Wang、Fayang G. Qiu、Junling Zhao
DOI:10.1016/j.tetlet.2018.03.069
日期:2018.5
A novel method for the stereoselectiveconjugateaddition of 3-substituted oxindoles to in situ generated o-QMs was described. This process was catalyzed efficiently by a cinchonidine-derived squaramide catalyst in oil-water phase, furnishing the corresponding 3,3-disubsituted oxindole derivatives in moderate to high yields (up to 98%) with high stereoselectivities (up to 95% ee, 15.4:1 dr). The utility
Counterion Control of
<i>t</i>
‐BuO‐Mediated Single Electron Transfer to Nitrostilbenes to Construct
<i>N</i>
‐Hydroxyindoles or Oxindoles
作者:Yingwei Zhao、Haoran Zhu、Siyoung Sung、Donald J. Wink、Joseph M. Zadrozny、Tom G. Driver
DOI:10.1002/anie.202104319
日期:2021.8.23
tert-Butoxide unlocks new reactivity patterns embedded in nitroarenes. Exposure of nitrostilbenes to sodium tert-butoxide was found to produce N-hydroxyindoles at room temperature without an additive. Changing the counterion to potassium changed the reaction outcome to yield solely oxindoles through an unprecedented dioxygen-transfer reaction followed by a 1,2-phenyl migration. Mechanistic experiments
A novel, one-pot, three-step synthetic method to prepare 2-aminobenzophenones from 2-alkynyl arylazides has been disclosed. This reaction is catalyzed by palladium to form 3-hydroxy-3-phenylindolin-2-ones, which is followed by hydrolysis of amide bonds and copper-catalyzed decarboxylation to generate 2-aminobenzophenones. The desired products are afforded in moderate to good yields under mild reaction
Herein, we present a general electrochemical method to access unsymmetrical 3,3-disubstituted oxindoles by direct C–H functionalization where the oxindole fragment behaves as an electrophile. This Umpolung approach does not rely on stoichiometric oxidants and proceeds under mild, environmentally benign conditions. Importantly, it enables the functionalization of these scaffolds through C–O, and by
We report an unexpected rearrangement of 3-hydroxyoxindoles into benzoxazinones using electrochemistry. Our reaction employs mild and environmentally friendly conditions, and the benzoxazinone products are obtained in moderate to excellent yields. Mechanistic experiments suggest that a peroxide intermediate is likely involved.