- Organocatalytic stereoselective conjugate addition of 3-substituted oxindoles with in situ generated ortho-quinone methides
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A novel method for the stereoselective conjugate addition 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 of this reaction was also investigated by the gram-scale synthesis and derivatization of one of the products.
- Liang, Weihong,Yin, Wenhao,Wang, Tingzhong,Qiu, Fayang G.,Zhao, Junling
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supporting information
p. 1742 - 1747
(2018/04/02)
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- Iron(iii)-salan complexes catalysed highly enantioselective fluorination and hydroxylation of β-keto esters and N-Boc oxindoles
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Chiral iron(iii)-salan complexes catalysed highly enantioselective α-fluorination and α-hydroxylation of β-keto esters and N-Boc oxindoles to give the corresponding products in high yields and good-to-excellent ee values under mild reaction conditions. This journal is the Partner Organisations 2014.
- Gu, Xin,Zhang, Yan,Xu, Zhen-Jiang,Che, Chi-Ming
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p. 7870 - 7873
(2014/07/08)
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- In situ generation of electrophilic trifluoromethylthio reagents for enantioselective trifluoromethylthiolation of oxindoles
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An organocatalytic asymmetric trifluoromethylthiolation reaction via in situ generation of active electrophilic trifluoromethylthio species involving trichloroisocyanuric acid and AgSCF3 as a practical and easily handled electrophilic SCF3 source for CSP 3-SCF3 bond formation was developed. Reactions with this one-pot version strategy occurred in good yields and excellent stereoselectivities to access enantiopure oxindoles bearing a SCF 3-substituted quaternary chiral center. The straightforward process described here makes use of simple starting materials and proceeds under mild conditions, which will be useful in medicinal chemistry and diversity-oriented syntheses.
- Zhu, Xing-Li,Xu, Jin-Hui,Cheng, Dao-Juan,Zhao, Li-Jiao,Liu, Xin-Yuan,Tan, Bin
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supporting information
p. 2192 - 2195
(2014/05/06)
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- Chincona alkaloid-catalyzed enantioselective trifluoromethylthiolation of oxindoles
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An organocatalytic asymmetric trifluoromethylthiolation of 3-aryl or 3-alkyloxindoles employing a trifluoromethyl-substituted thioperoxide as the electrophilic trifluoromethylthiolating reagent was described. Reactions occurred in good to excellent enanti
- Yang, Tao,Shen, Qilong,Lu, Long
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p. 678 - 680
(2014/10/16)
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- Enantioselective construction of tetrasubstituted stereogenic carbons through bronsted base catalyzed michael reactions: α′-hydroxy enones as key enoate equivalent
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Catalytic and asymmetric Michael reactions constitute very powerful tools for the construction of new C-C bonds in synthesis, but most of the reports claiming high selectivity are limited to some specific combinations of nucleophile/electrophile compound types, and only few successful methods deal with the generation of all-carbon quaternary stereocenters. A contribution to solve this gap is presented here based on chiral bifunctional Bronsted base (BB) catalysis and the use of α′-oxy enones as enabling Michael acceptors with ambivalent H-bond acceptor/donor character, a yet unreported design element for bidentate enoate equivalents. It is found that the Michael addition of a range of enolizable carbonyl compounds that have previously demonstrated challenging (i.e., α-substituted 2-oxindoles, cyanoesters, oxazolones, thiazolones, and azlactones) to α′-oxy enones can afford the corresponding tetrasubstituted carbon stereocenters in high diastereo- and enantioselectivity in the presence of standard BB catalysts. Experiments show that the α′-oxy ketone moiety plays a key role in the above realizations, as parallel reactions under identical conditions but using the parent α,β-unsaturated ketones or esters instead proceed sluggish and/or with poor stereoselectivity. A series of trivial chemical manipulations of the ketol moiety in adducts can produce the corresponding carboxy, aldehyde, and ketone compounds under very mild conditions, giving access to a variety of enantioenriched densely functionalized building blocks containing a fully substituted carbon stereocenter. A computational investigation to rationalize the mode of substrate activation and the reaction stereochemistry is also provided, and the proposed models are compared with related systems in the literature.
- Badiola, Eider,Fiser, Bla,Gmez-Bengoa, Enrique,Mielgo, Antonia,Olaizola, Iurre,Urruzuno, Iaki,Garca, Jess M.,Odriozola, Jos M.,Razkin, Jess,Oiarbide, Mikel,Palomo, Claudio
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p. 17869 - 17881
(2015/02/19)
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- Facile synthesis of enantioenriched Cγ-tetrasubstituted α-amino acid derivatives via an asymmetric nucleophilic addition/protonation cascade
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Chemical equations presented. An asymmetric nucleophilic addition/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 simply by changing cinchonidine-derived catalyst to the cinchonine analogue.
- Duan, Shu-Wen,An, Jing,Chen, Jia-Rong,Xiao, Wen-Jing
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supporting information; experimental part
p. 2290 - 2293
(2011/06/22)
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- Catalytic enantioselective fluorination of oxindoles
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We have developed a highly efficient catalytic enantioselective fluorination of oxindole derivatives. In the presence of a catalytic amount of chiral Pd complex 2 (2.5 mol %), various substrates, including aryl- and alkyl-substituted oxindoles, were fluor
- Hamashima, Yoshitaka,Suzuki, Toshiaki,Takano, Hisashi,Shimura, Yuta,Sodeoka, Mikiko
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p. 10164 - 10165
(2007/10/03)
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