Highly Enantioselective Friedel−Crafts Reaction of Indoles with Imines by a Chiral Phosphoric Acid

Kang, Qiang; Zhao, Zhuo‐An; You, Shu‐Li

doi:10.1021/ja067417a

Cited by 400 publications

(125 citation statements)

References 10 publications

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“…If the Z configuration is energetically inaccessible the reaction proceeds via a Type I E pathway, the correct catalyst has large proximal and medium AREA(θ) 10, 11, 12, 13c, 14b, 19, 20, 21, 22, 40, 41, 42, 43, 44, 45, 46, 47. However, reactions involving displaced nucleophiles the best choice of catalyst has large proximal and small AREA(θ) 5, 8, 9, 30, 31, 48, 49, 50, 51, 52, 53. Higher enantioselectivities with small proximal bulk catalysts are not uncommon with displaced nucleophiles.…”

Section: Resultsmentioning

confidence: 99%

Selecting Chiral BINOL‐Derived Phosphoric Acid Catalysts: General Model To Identify Steric Features Essential for Enantioselectivity

Reid

Goodman

2017

Chemistry A European J

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Choosing the optimal catalyst for a new transformation is challenging because the ideal molecular requirements of the catalyst for one reaction do not always simply translate to another. Large groups at the 3,3′ positions of the binaphthol rings are important for efficient stereoinduction but if they are too large this can lead to unusual or poor results. By applying a quantitative steric assessment of the substituents at the 3,3′ positions of the binaphthol ring, we have systematically studied the effect of modulating this group on enantioselectivity for a wide range of reactions involving imines, and verified this analysis using ONIOM calculations. We have shown that in most reactions, the stereochemical outcome depends on both proximal and remote sterics. Summarising detailed calculations into a simple qualitative model identifies and explains the steric features required for high selectivity. This model is consistent with seventy seven papers reporting reactions (over 1000 transformations in total), and provides a straightforward decision tree for selecting the best catalyst.

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Section: Resultsmentioning

confidence: 99%

Selecting Chiral BINOL‐Derived Phosphoric Acid Catalysts: General Model To Identify Steric Features Essential for Enantioselectivity

Reid

Goodman

2017

Chemistry A European J

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“…[28][29][30] Moreover, Friedel-Crafts alkylation of indole with N-tosylaldimine to form a compound similar to 4 in the presence of a Brønsted acid has been reported. [31][32][33][34][35] However, these synthetic methods are limited, we are convinced that our reaction using a nitrile is worth studying. This work, as well as the acylation described in Tables 2-4, began synthesizing an electrophilic substitution reaction by a combination of a variety of indoles and various nitriles to result in the iminium intermediate (2).…”

Section: Resultsmentioning

confidence: 99%

A New Methodology for Functionalization at the 3-Position of Indoles by a Combination of Boron Lewis Acid with Nitriles

Mizoi

Mashima

Kawashima

et al. 2015

CHEMICAL & PHARMACEUTICAL BULLETIN

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We discovered that a reagent comprising a combination of PhBCl 2 and nitriles was useful for syntheses of both 3-acylindoles and 1-(1H-indol-3-yl)alkylamine from indoles. The reaction proceeded selectively at the 3-position of indoles providing 3-acylindoles in moderate to high yields on treatment with the above reagent. Furthermore, the reaction provided the corresponding amine products in moderate to high yields after the intermediate imine was reduced by NaBH 3 CN. These reactions proceeded under mild conditions and are applicable to the formation of indoles functionalized at the 3-position.Key words boron Lewis acid; nitrile; indole; 3-acylindole; 1-(1H-indol-3-yl)alkylamine Sugasawa et al. reported that aniline underwent FriedelCrafts type acylation with nitrile in the presence of BCl 3 .

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“…6 The large amounts of conventional Lewis acids usually required to promote typical Friedel-Crafts alkylation processes represent serious drawbacks (poor regioselectivities, undesired side-reactions of the electrophile, environmental concerns,…). In addition, the alkylation of indolyl compounds is usually performed with typical electrophiles such as carbonyl compounds, 7 imines, 8 electron-deficient C=C bonds, 9 epoxides and aziridines. 10 Also, the well-known Pd-catalyzed allylic substitution (Tsuji-Trost reaction) represents a useful approach.…”

Section: Introductionmentioning

confidence: 99%

Brønsted Acid Catalyzed Alkylation of Indoles with Tertiary Propargylic Alcohols: Scope and Limitations

et al. 2010

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The direct alkylation of indoles with a wide variety of tertiary propargylic alcohols under Brønsted acid catalysis has been studied. A general and environmentally friendly method for the synthesis of C3-propargylated indoles with a quaternary carbon at the propargylic position has been developed. The reactions are highly regioselective regarding both the indole and the alkynol counterparts.Only with N-unsubstituted-2-arylindoles a competitive S N´ reaction takes place affording 3-dienyl or 3-allenylindoles depending on the alkynol moiety. Reactions have been carried out in air with undried solvent, and water was the only side product.____________ [a]

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Highly Enantioselective Friedel−Crafts Reaction of Indoles with Imines by a Chiral Phosphoric Acid

Abstract: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Cited by 400 publications

References 10 publications

Selecting Chiral BINOL‐Derived Phosphoric Acid Catalysts: General Model To Identify Steric Features Essential for Enantioselectivity

Selecting Chiral BINOL‐Derived Phosphoric Acid Catalysts: General Model To Identify Steric Features Essential for Enantioselectivity

A New Methodology for Functionalization at the 3-Position of Indoles by a Combination of Boron Lewis Acid with Nitriles

Brønsted Acid Catalyzed Alkylation of Indoles with Tertiary Propargylic Alcohols: Scope and Limitations

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