Bifunctional tertiary amine-squaramide catalyzed asymmetric catalytic 1,6-conjugate addition/aromatization of para-quinone methides with oxindoles
作者:Yu-Hua Deng、Xiang-Zhi Zhang、Ke-Yin Yu、Xu Yan、Ji-Yuan Du、Hanmin Huang、Chun-An Fan
DOI:10.1039/c5cc10502a
日期:——
Asymmetric catalytic 1,6-addition of p-QMs with racemic oxindoles under the bifunctionalcatalysis of C2-symmetric dimeric Cinchona-derived squaramides is described. This tertiary amine-squaramide catalzyed reaction provides a diastereoselective and enantioselective approach...
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
protected 3-hydrazino fragment into the corresponding primary amine was also demonstrated, to expand the synthetic flexibility of asymmetric electrophilic amination with azo-dicarboxylic esters en route to enantioenriched 3-amino-2-oxindoles. The absolute configuration of 3-amino-3-phenyl-2-oxindole was independently established by electronic circular dichroism (ECD), combined with time-dependent density
Organocatalytic Michael addition of unprotected 3-substituted oxindoles to nitroolefins
作者:Miao Ding、Feng Zhou、Zi-Qing Qian、Jian Zhou
DOI:10.1039/c004037a
日期:——
Quinidine was found to catalyze the Michaeladdition of unprotected 3-substitutedoxindoles to nitroolefins in excellent yield and moderate to good diastereoselectivity. Bifunctional quinidine derived thioureacatalyst 10 could catalyze this reaction to afford the major diastereomer in up to 85% ee.
Facile Synthesis of Enantioenriched C<sup>γ</sup>-Tetrasubstituted α-Amino Acid Derivatives via an Asymmetric Nucleophilic Addition/Protonation Cascade
An asymmetricnucleophilicaddition/protonation reaction of 3-substituted oxindoles and ethyl 2-phthalimidoacrylate has been described. This strategy can give direct access to Cγ-tetrasubstituted α-amino acid derivatives bearing 1,3-nonadjacent stereocenters with up to 98% yield, 94:6 dr, and >99% ee. Dual activation is proposed in the transition state, and the opposite enantiomers can be obtained