- Zwitterion-Catalyzed Isomerization of Maleic to Fumaric Acid Diesters
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Fumaric acid diesters are important building blocks for organic synthesis. A class of zwitterionic organocatalysts based on an amide anion/iminium cation charge pair were found to be effective in catalyzing the isomerization of maleic acid diesters to give fumaric acid diesters. Comparison of the performance of different zwitterionic organocatalysts toward the reaction revealed that nonclassical hydrogen bonding was involved in the stabilization of the Michael adduct intermediate.
- Lam, Ying-Pong,Lam, Zachary,Yeung, Ying-Yeung
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p. 1183 - 1190
(2021/01/09)
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- Enantioselective Synthesis of N-Alkylamines through β-Amino C-H Functionalization Promoted by Cooperative Actions of B(C6F5)3and a Chiral Lewis Acid Co-Catalyst
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We disclose a catalytic method for β-C(sp3)-H functionalization of N-alkylamines for the synthesis of enantiomerically enriched β-substituted amines, entities prevalent in pharmaceutical compounds and used to generate different families of chiral catalysts. We demonstrate that a catalyst system comprising of seemingly competitive Lewis acids, B(C6F5)3, and a chiral Mg- or Sc-based complex, promotes the highly enantioselective union of N-alkylamines and α,β-unsaturated compounds. An array of δ-amino carbonyl compounds was synthesized under redox-neutral conditions by enantioselective reaction of a N-alkylamine-derived enamine and an electrophile activated by the chiral Lewis acid co-catalyst. The utility of the approach is highlighted by late-stage β-C-H functionalization of bioactive amines. Investigations in regard to the mechanistic nuances of the catalytic processes are described.
- Chang, Yejin,Cao, Min,Chan, Jessica Z.,Zhao, Cunyuan,Wang, Yuankai,Yang, Rose,Wasa, Masayuki
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supporting information
p. 2441 - 2455
(2021/02/16)
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- Efficient synthesis of symmetrical phthalate and maleate diesters using phosphinite ionic liquids
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Symmetrical dialkyl phthalates and maleates were synthesized using phosphinite ionic liquid as a catalyst and reaction medium. The results indicated that phosphinite ionic liquid shows better catalytic and reusable performance without using any acid or base catalyst. Under the optimum conditions, using 1-methyl-3-(4-phosphinitebutyl) imidazolium chloride as catalyst, the conversion of phthalic and maleic anhydrides to the corresponding diesters of primary and secondary alcohols was occurred in 72-85% yields. The diesters of tertiary alcohols and phenols could not be prepared by this method. A kind of widely used plasticizer, dioctyl phthalate, was prepared in good yield under these conditions. The ionic liquid could be reused three times after easy separation from the products without any disposal. Iranian Chemical Society 2012.
- Valizadeh,Khalili
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p. 529 - 534
(2013/02/22)
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- Highly chemo- and stereoselective intermolecular coupling of diazoacetates to give cis-olefins by using Grubbs second-generation catalyst
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Highly stereoselective formation of cis-2-ene-1,4-diesters by homo- and heterocoupling of α-diazoacetates in the presence of Grubbs second-generation catalyst is demonstrated. The dual reactivity of the catalyst in alkene metathesis and diazocoupling has been exploited in the synthesis of 12-26-membered macrocyclic dienyl dilactones by one-pot carbene dimerisation/ring-closing metathesis.
- Hodgson, David M.,Angrish, Deepshikha
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p. 3470 - 3479
(2008/02/08)
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- Reactions of Wittig Reagents with Episulfides or Elemental Sulfur
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The reactions of Wittig reagents with episulfides gave symmetrical olefins and triphenylphosphine sulfide in moderate yields.The same olefins were obtained by reactions of Wittig reagents with elementar sulfur.These reactions might proceed through thiocarbonyl intermediates, the existence of which was confirmed by Diels-Alder reactions with dienes.
- Okuma, Kentaro,Tachibana, Yuji,Sakata, Jun-ichi,Komiya, Takashi,Kaneko, Isao,et al.
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p. 4323 - 4328
(2007/10/02)
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- Reactions of Stable Wittig Reagents with Episulfides
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Stable Wittig reagents effectively reacted with episulfides to afford dialkyl fumarates and maleates in good yields.The reaction probably occured via attack of the ylide carbanion on episulfide's sulfur to form a thiocarbonyl intermediate.The ylide further attacked this thiocarbonyl intermediate to give the final olefins.
- Okuma, Kentaro,Yamasaki, Yusuke,Komiya, Takashi,Kodera, Yasushi,Ohta, Hiroshi
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p. 356 - 360
(2007/10/02)
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