Structure of indolylphenylmethyl cations

Kogan, N. A.; Kul'bitskii, G. N.

doi:10.1007/bf00635941

Cited by 10 publications

(4 citation statements)

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“…Based on the results of Tamamura’s mechanistic studies, we propose a catalytic process involving cation–π interaction of an indole/imidazolium complex, which increases the acidity of the indole, enabling deprotonating of the complex by the chloride anion. The intermediate (1 H -indol-3-yl)(aryl)methanol is expected to ionize to an indolylphenylmethyl cationic species based on literature precedent,[40–42] which rapidly reacts with another molecule of indole to furnish the isolated bis(indolyl)methanes products. The inability to isolate the intermediate (1 H -indol-3-yl)(aryl)methanol suggests the second step is very rapid.…”

Section: Resultsmentioning

confidence: 99%

Development of an imidazole salt catalytic system for the preparation of bis(indolyl)methanes and bis(naphthyl)methane

Wang

Aldrich

2019

PLoS ONE

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Imidazolium salts are shown to catalyze the rapid room temperature reaction of indoles or naphthol with aldehydes to provide bis(indolyl)methanes or bis(naphthol)methane in excellent yields and the reaction proceeds optimally in dichloromethane with no base additives. The reaction exhibits a broad substrate tolerance and occurs through nucleophilic activation of the indoles and naphthols through a cation–π interaction.

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Section: Resultsmentioning

confidence: 99%

Development of an imidazole salt catalytic system for the preparation of bis(indolyl)methanes and bis(naphthyl)methane

Wang

Aldrich

2019

PLoS ONE

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“…3‐Indolylmethanols can undergo dehydration reaction in the presence of acid to generate transient vinyliminium intermediates , which are highly active electrophiles and have been employed in reactions with numerous nucleophiles to construct a wide variety of indole derivatives . We envisaged that, as a kind of excellent nucleophiles, 3‐isothiocyanato oxindoles would participate in cyclization with the vinyliminium intermediates generated from 3‐indolylmethanols.…”

Section: Introductionmentioning

confidence: 99%

Construction of Novel Tetrahydro‐β‐carboline‐1‐thione Spirooxindoles by Brønsted Acid Mediated Formal [3+3] Cyclization of 3‐Indolylmethanols with 3‐Isothiocyanato Oxindoles

Liao

Bai

Shibata

et al. 2016

Journal of Heterocyclic Chem

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p‐Toluenesulfonic acid mediated formal [3+3] cyclization of 3‐indolylmethanols with 3‐isothiocyanato oxindoles was realized. This transformation allowed for the synthesis of a series of novel tetrahydro‐β‐carboline‐1‐thione spirooxindoles in moderate to excellent yields (up to 99%) with generally good diastereoselectivities (up to >20:1). The structure of one product was determined by an X‐ray crystal structural analysis.

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“…近年来, 利用金属催化合成不同位置取代的四氢-β-咔啉衍生物的方法取得到了一定的进展 [3] 3-吲哚基取代甲醇类化合物在酸性条件下易失去一分子水形成吲哚基稳定的碳正离子 [4] , 原位形成的活性正离子中间体作为良好的亲电试剂可以与不同的亲核物种发生反应, 故以 3-吲哚基取代甲醇为亲电底物的反应被用于不对称催化合成不同的重要吲哚碱类化合物 [5～8] . 但是, 这些反应多集中在与不同的亲核试剂发生的加成反应, 利用 3-吲哚基取代甲醇类化合物进行的环加成反应只有少数报道 [9] .…”

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Chiral Brønsted Acid Catalyzed Stereoselective [3+3] Cycloaddition Reaction of Azomethine Ylide to Vinylimine Intermediates: Constructing Fully Functionalized Chiral Tetrahydro-β-Carboline

黄建洲¹,

罗时玮²,

龚流柱³

2013

Acta Chim. Sinica

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An asymmetric three-component formal [3＋3] cycloaddition reaction of aldehyde, diethyl 2-aminomalonate and substituted indolyl alcohols, has been investigated with chiral BINOL-derived monophosphoric acids as catalysts. The active azomethine ylide intermediate can be readily formed from the condensation of aldehyde and diethyl 2-aminomalonate under the promotion of the chiral phosphoric acids and is thereby able to undergo nucleophilic addition reaction to electron-deficient carbon-carbon double bonds as reported previously in the multicomponent reactions. On the other hand, the indolyl alcohols are able to participate in a dehydration reaction in the presence of the phosphoric acids to generate transient vinyliminium intermediates, which are principally reactive toward nucleophiles. Thus, we envisioned that the two types of active intermediates could undergo an asymmetric formal [3＋3] cycloaddition to stereoselectively produce functionalized tetrahydro-β-carbolines under the catalysis of the chiral phosphoric acids. Consequently, a variety of 3,3'-disubstituted BINOL-phosphoric acids were initially evaluated for the reaction. As a result, the 3,3'-bis(p-ClPh) BINOL-phosphoric acid proved to perform most successfully in non-polar solvents, such as toluene. This reaction actually provides a highly straightforward access to functionalized tetrahydro-β-carboline derivatives. A number of substituted indolyl alcohols bearing either electronically donating or withdrawing groups are well tolerated, affording highly functionalized tetrahydro-β-carbolines in high yields ranging from 70% to 91% and with excellent enantioselectivities of up to 93% ee. A representative procedure for the enantioselective formal [3＋3] cycloaddition reaction is as following: After a mixture of p-nitrobenzaldehyde (0.06 mmol), diethyl 2-amino-malonate (0.05 mmol), 3 Å MS (100 mg) and chiral phosphoric acid (10 mol%) in toluene (1.0 mL) was stirred at the r.t. for 15 min, the substituted indolyl acohol (0.1 mmol) was added. After completion of the addition, the reaction mixture was stirred for additional 12 h at the same temperature. The reaction solution was filtrated and the residue was washed three times with ethyl acetate (5 mL×3). The combined organic solutions were evaporated under the reduced pressure to give corresponding crude products, which were purified by column chromatography on silica gel (eluent: light petroleum ether∶ethyl acetate, V∶V＝3∶1) to give analytically pure tetrahydro-β-carboline derivatives.

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Structure of indolylphenylmethyl cations

Cited by 10 publications

References 2 publications

Development of an imidazole salt catalytic system for the preparation of bis(indolyl)methanes and bis(naphthyl)methane

Development of an imidazole salt catalytic system for the preparation of bis(indolyl)methanes and bis(naphthyl)methane

Construction of Novel Tetrahydro‐β‐carboline‐1‐thione Spirooxindoles by Brønsted Acid Mediated Formal [3+3] Cyclization of 3‐Indolylmethanols with 3‐Isothiocyanato Oxindoles

Chiral Brønsted Acid Catalyzed Stereoselective [3+3] Cycloaddition Reaction of Azomethine Ylide to Vinylimine Intermediates: Constructing Fully Functionalized Chiral Tetrahydro-β-Carboline

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