Highly Enantioselective Bromocyclization of Tryptamines and Its Application in the Synthesis of (−)‐Chimonanthine

Xie, Weiqing; Jiang, Guangde; Liu, Huan; Hu, Jiadong; Pan, Xixian; Zhang, Hui; Wan, Xiaolong; Lai, Yisheng; Ma, Dawei

doi:10.1002/anie.201306774

Cited by 231 publications

(69 citation statements)

References 63 publications

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“…48 Later work by the same authors on a closely related bromocyclization found that mixtures of “monocationic” and “tricationic” DABCO-derived “Br + ” salts closely related to 22 and 19 gives optimal performance. 49 …”

Section: Challenges For Stereoselective Catalysismentioning

confidence: 99%

Catalytic, Stereoselective Dihalogenation of Alkenes: Challenges and Opportunities

2015

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Although recent years have witnessed significant advances in the development of catalytic, enantioselective halofunctionalizations of alkenes, the related dihalogenation of olefins to afford enantioenriched vicinal dihalide products remains comparatively underdeveloped. However, the growing number of complex natural products bearing halogen atoms at stereogenic centers has underscored this critical gap in the synthetic chemist's arsenal. This Review highlights the selectivity challenges inherent in the design of enantioselective dihalogenation processes, and formulates a mechanism-based classification of alkene dihalogenations, including those that may circumvent the "classical" haliranium (or alkene-dihalogen π-complex) intermediates. A variety of metal and main group halide reagents that have been used for the dichlorination or dibromination of alkenes are discussed, and the proposed mechanisms of these transformations are critically evaluated. AbstractCatalysis of alkene dihalogenation , under different activation modes, with control over both the absolute and relative stereochemical course of dihalogen addition, is one of the most vexing problems in stereoselective synthesis. Dihalogenations that circumvent the "classical" haliranium (or alkene-dihalogen π complex) intermediates provide new and exciting opportunities for catalysis, potentially having broader implications for the design of stereoselective alkene difunctionalizations.

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Section: Challenges For Stereoselective Catalysismentioning

confidence: 99%

Catalytic, Stereoselective Dihalogenation of Alkenes: Challenges and Opportunities

2015

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“…Displacement of C3a-bromo pyrroloindolines can be achieved with the use of stoichiometric base, but these reactions typically only function well when an ester is present at C2. 10 Otherwise silver salts are often utilized, 11 but these conditions often require the use of superstoichiometric amounts of these expensive reagents. Single electron transfer conditions have also been explored for substitution of the bromide with carbon nucleophiles.…”

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confidence: 99%

Lewis Acid Catalyzed Displacement of Trichloroacetimidates in the Synthesis of Functionalized Pyrroloindolines

Adhikari

Chisholm

2016

Org. Lett.

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The pyrroloindoline core is found in many natural products. These structures often differ at the C3a position, which may be substituted with an oxygen, nitrogen, sp3 or sp2 hybridized carbon. Utilizing a trichloroacetimidate leaving group, a diversity-oriented approach to these structures has been developed. The trichloroacetimidate intermediate allows for the rapid incorporation of anilines, alcohols, thiols and carbon nucleophiles. This method was applied in the synthesis of arunidinine and a formal synthesis of psychotriasine.

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“…[4][5][6] Recently, asymmetric anionic phase-transfer reactions 7,8) have been reported using chiral phosphates with an aziridinium cation 9) and N-haloammonium cations. [10][11][12][13][14][15][16][17][18] …”

mentioning

confidence: 99%

Acceleration of Acid-Catalyzed Hydrolysis in a Biphasic System by Sodium Tetracyanocyclopentadienides

Sakai

Bito

Itakura

et al. 2016

CHEMICAL & PHARMACEUTICAL BULLETIN

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The hydrolysis of tert-butyldimethylsilyl L-menthyl ether (3) in a CH 2 Cl 2 -1 M HCl biphasic solvent system was accelerated by the addition of sodium tetracyanocyclopentadienides 1. Particularly, the reaction rate was enhanced using sodium salt 1a-c with a lipophilic substituent on the cyclopentadienide ring. From the results obtained by a triphasic experiment, hydrolysis proceeds via the formation of hydronium ion 2 in the aqueous phase by ion exchange, followed by the transfer of 2 to the CH 2 Cl 2 phase.Key words phase-transfer reaction; hydrolysis; tetracyanocyclopentadienide; acid-catalyzed reaction Phase-transfer reactions have garnered increasing attention in organic chemistry because of their mild, sustainable conditions. 1) Phase-transfer catalysts (PTCs) enhance the reactivity of anionic reagents by forming a lipophilic ion pair, mediating a reaction in the organic phase or at the interface between two phases. Enantioselective phase-transfer reactions catalyzed by chiral quaternary ammonium salts are one of the representative methods for synthesizing optically active molecules.2,3) Anionic PTCs have also been developed for reactions where lipophilic anions enhance the solubility of the reactive cationic species, thereby promoting the reactions. Kobayashi et al. have reported the first anionic phase-transfer reaction using tetrakis(3,5-bis(trifluoromethyl) phenyl) borate (TFPB) anion. [4][5][6] Recently, asymmetric anionic phase-transfer reactions 7,8) have been reported using chiral phosphates with an aziridinium cation 9) and N-haloammonium cations. [10][11][12][13][14][15][16][17][18]

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Highly Enantioselective Bromocyclization of Tryptamines and Its Application in the Synthesis of (−)‐Chimonanthine

Cited by 231 publications

References 63 publications

Catalytic, Stereoselective Dihalogenation of Alkenes: Challenges and Opportunities

Catalytic, Stereoselective Dihalogenation of Alkenes: Challenges and Opportunities

Lewis Acid Catalyzed Displacement of Trichloroacetimidates in the Synthesis of Functionalized Pyrroloindolines

Acceleration of Acid-Catalyzed Hydrolysis in a Biphasic System by Sodium Tetracyanocyclopentadienides

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