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Lewis Acid (lewi + acid)

Distribution by Scientific Domains
Chemistry88%
Polymers and Materials Science9%
2 Other Domains3%
Distribution within Chemistry
Organic Chemistry69%
General & Introductory Chemistry13%
7 Other Subdomains18%

Kinds of Lewis Acid

  • chiral Lewi acid
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    Terms modified by Lewis Acid

  • Lewi acid catalysis
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  • Lewi acid catalyst
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  • Lewi acid site
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    Selected Abstracts

    Lewis Acid Mediated Aminobenzannulation Reactions of ,-Ketoalkynes: Synthesis of 1-Aminocarbazoles and 9-Aminopyrido[1,2- a]indoles

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 17 2009
    Diego Facoetti
    Abstract 2-Acyl- N -propargylindoles 1 and 2-acyl-3-propargylindoles 5 undergo aminobenzannulation reactions with pyrrolidine in the presence of an appropriate Lewis acid to give 9-aminopyrido[1,2- a]indoles 6 and 1-aminocarbazoles 7, respectively. The selection of the appropriate Lewis acid, TiCl4 or GaCl3 for 1 and InCl3 for 5, allows the domino process involving the initial formation of an enamine intermediate, followed by a regioselective 6- exo - dig intramolecular nucleophilic attack of the nucleophilic terminus of the unsaturated system (the ,-carbon of the enamino moiety) to the carbon,carbon triple bond. Moreover, several features concerning the reaction mechanism and the role of both catalysts, in connection with the electronic properties of the reacting alkynes, are reported. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

    Lewis Acid Induced [2+2] Cycloadditions of Silyl Enol Ethers with ,,,-Unsaturated Esters: A DFT Analysis

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 18 2005
    Manuel Arnó
    Abstract The Lewis acid (LA) induced cycloaddition of trimethysilyl vinyl ether with methyl acrylate has been studied by DFT methods at the B3LYP/6-31G* level. In the absence of an LA, a [4+2] cycloaddition between the silyl enol ether and methyl acrylate in the s-cis conformation takes place through an asynchronous, concerted bond-formation process. This cycloaddition presents a large activation enthalpy of 21.1 kcal,mol,1. Coordination of the LA AlCl3 to the carbonyl oxygen atom of methyl acrylate yields a change of molecular mechanism from a concerted to a two-step mechanism and produces a drastic reduction of the activation energy. This stepwise mechanism is initialized by the nucleophilic attack of the enol ether at the ,-position of methyl acrylate in a Michael-type addition. The very low activation energy (7.1 kcal,mol,1)associated with this nucleophilic attack can be related to the increase of the electrophilicity of the LA-coordinated ,,,-unsaturated ester, which favors the cycloaddition through a polar process. The subsequent ring-closure allows the formation of the corresponding [2+2] and [4+2] cycloadducts. While the [4+2] cycloadduct is formed by kinetic control, the [2+2] cycloadducts are formed by thermodynamic control. The energetic results provide an explanation for the conversion of [4+2] cycloadducts into the thermodynamically more stable [2+2] ones. The cis/trans ratio found for the catalytic [2+2] process is in agreement with the experimental outcome. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

    The Formation of Silylated ,-Lactams from Silylketenes through Lewis Acid Promoted [2+2] Cycloaddition: A Combined Theoretical and Experimental Study

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 12 2005
    Béatrice Pelotier
    Abstract The stereoselective formation of silylated cis -,-lactams from (trimethylsilyl)ketene and an ,-imino ester by Lewis acid catalysis is described. Theoretical results suggest that the reaction between (trimethylsilyl)ketene and trans -(methoxycarbonyl)- N -methylformaldimine would proceed most favourably with the BF3 catalyst coordinated to the ketene. Moreover, the calculated energy barriers account for the cis:trans ratio found experimentally. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

    A Lewis Acid Promoted Asymmetric Umpolung Reaction with ChiralN -Sulfinyl Imines as the Electrophiles

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 9 2005
    Xin Xu
    Abstract An new asymmetric umpolung reaction has been developed by reacting N -sulfinyl imines with 2-lithio-2-phenyl-1,3-dithiane. The reaction was conducted at between ,20 and,25 °C in THF in the presence of Et2AlCl as the Lewis acid promoter. Excellent diastereoselectivities (up to >95,% de) and chemical yields (64,95,%) have been achieved for nine substrates with all individual isomers separated and characterized. The absolute structure of the chiral products has been unambiguously determined by synthetic conversions to a known sample. 2-Lithio-2-phenyl-1,3-dithiane was found to be much less reactive than its 2-methyl counterpart, which was reported very recently. All individual isomers have been readily separated by column chromatography. The absolute structure of the chiral products has been unambiguously determined by conversion into a known compound. This method provides an easy access to enantiomerically pure ,-amino ketones. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

    Aqueous Asymmetric Mukaiyama Aldol Reaction Catalyzed by Chiral Gallium Lewis Acid with Trost-Type Semi-Crown Ligands

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2005
    Hui-Jing Li
    Abstract The combination of Ga(OTf)3 with chiral semi-crown ligands (1a,e) generates highly effective chiral gallium Lewis acid catalysts for aqueous asymmetric aldol reactions of aromatic silyl enol ethers with aldehydes. A ligand-acceleration effect was observed. Water is essential for obtaining high diastereoselectivity and enantioselectivity. The p -phenyl substituent in aromatic silyl enol ether (2,h) plays an important role and increases the enantioselectivity up to 95% ee. Although aliphatic silyl enol ethers provided low enantioselectivities and silylketene acetal is easily hydrolyzed in aqueous alcohol, the aldol reactions of silylketene thioacetal (12) with aldehydes in the presence of gallium-Lewis acid catalysts give the ,-hydroxy thioester with reasonable yields and high diastereo- (up to 99,:,1) and enantioselectivities (up to 96% ee). [source]

    Soluble Molecular Dimers of CaO and SrO Stabilized by a Lewis Acid,

    ANGEWANDTE CHEMIE, Issue 46 2009
    Pillai Sarish Dipl.-Chem., Sankaranarayana
    Lösliche Oxide: Die Reaktion zwischen einem ,-Diketiminat-Aluminium(methyl)hydroxid und [M{N(SiMe3)2}2(thf)2] (M=Ca, Sr) resultiert in Erdalkalimetalloxiden wie [{LAl(Me)(,-O)Ca(thf)}2] (siehe Struktur ohne Arylreste; L steht für das deprotonierte ,-Diketiminat CH{C(CH2)}(CMe)(2,6- iPr2C6H3N)2). Diese löslichen Komplexe liegen im Festkörper als Dimere mit beispiellosen M2O2 -Kernen vor. [source]

    Building Addressable Libraries: Site-Selective Lewis Acid (Scandium(III)) Catalyzed Reactions,

    ANGEWANDTE CHEMIE, Issue 32 2009
    Bo Bi
    Gezielt verankert: Mikroelektroden-Arrays mit 1024 oder 12,544 Elektroden pro cm2 wurden für ortsselektive Lewis-Säure-katalysierte Reaktionen eingesetzt. Eine an den Elektroden erzeugte ScIII -Spezies fungiert als die Lewis-Säure, und das Reagens wird mithilfe eines Reduktionsmittels an die Elektroden fixiert. Die Strategie ließ sich auf eine Mehrkomponentensynthese von Tetrahydropyran (siehe Schema), eine Diels-Alder-Reaktion und eine Veresterung anwenden. [source]

    ChemInform Abstract: Zirconium Tetrakis(dodecyl Sulfate) [Zr(DS)4] as an Efficient Lewis Acid,Surfactant Combined Catalyst for the Synthesis of Quinoxaline Derivatives in Aqueous Media.

    CHEMINFORM, Issue 32 2009
    Alireza Hasaninejad
    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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    ChemInform Abstract: Lewis Acid or Broensted Acid Catalyzed Reactions of Vinylidene Cyclopropanes with Activated Carbon,Nitrogen, Nitrogen,Nitrogen, and Iodine,Nitrogen Double-Bond-Containing Compounds.

    CHEMINFORM, Issue 21 2009
    Jian-Mei Lu
    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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    ChemInform Abstract: Substrate-Controlled Selective Proximal and Distal C,C Bond Cleavage via Lewis Acid Mediated O-Acylation of 2-(Arylmethylene)cyclopropylaldehyde: A Stereoselective Synthesis of Bifunctional Methylenecyclobutanes and 1,3-Conjugated Dienes.

    CHEMINFORM, Issue 3 2009
    Xian Huang
    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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    ChemInform Abstract: Lewis Acid Mediated Reactions of 1-Cyclopropyl-2-arylethanone Derivatives with Allenic Ester, Ethyl Acetoacetate, and Methyl Acrylate.

    CHEMINFORM, Issue 49 2008
    Min Shi
    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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    ChemInform Abstract: Switchable Reactivity of Acylated ,,,-Dehydroamino Ester in the Friedel,Crafts Alkylation of Indoles by Changing the Lewis Acid.

    CHEMINFORM, Issue 49 2008
    Elena Angelini
    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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    ChemInform Abstract: Lewis Acid Promoted Carbon,Carbon Bond Cleavage of ,-Silyloxy-,-hydroxy-,-diazoesters.

    CHEMINFORM, Issue 32 2008
    Cristian Draghici
    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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    ChemInform Abstract: Unexpected Lewis Acid Mediated Reactions of 1-Arylbut-3-en-1-ols with Trimethyl Orthoformate , A New Synthesis of Homoallyl Ethers and Chlorides.

    CHEMINFORM, Issue 32 2008
    Elena Merisor
    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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    ChemInform Abstract: Lewis Acid Promoted Tandem Intermolecular Diels,Alder/Intramolecular Allylation Reactions of Silyl-Substituted 1,3-Butadienes Leading to Multisubstituted 7-Norbornenones and Related Polycyclic Compounds.

    CHEMINFORM, Issue 21 2008
    Dongzhen Li
    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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    ChemInform Abstract: Lewis Acid and Organocatalyst Cocatalyzed Multicomponent Reactions of 2-Alkynylbenzaldehydes, Amines, and Ketones.

    CHEMINFORM, Issue 16 2008
    Qiuping Ding
    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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    ChemInform Abstract: Lewis Acid Mediated Reactions of 1-Cyclopropyl-2-arylethanones with Allenic Esters: A Facile Synthetic Protocol for the Preparation of Dihydrofuro[2,3-h]chromen-2-one Derivatives.

    CHEMINFORM, Issue 12 2008
    Min Shi
    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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    ChemInform Abstract: InCl3/I2 -Catalyzed Cross-Coupling of Alkyl Trimethylsilyl Ethers and Allylsilanes via an in situ Derived Combined Lewis Acid of InCl3 and Me3SiI.

    CHEMINFORM, Issue 10 2008
    Takahiro Saito
    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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    ChemInform Abstract: Mild and Efficient Lewis Acid Promoted Detritylation in the Synthesis of N-Hydroxy Amides: A Concise Synthesis of (-)-Cobactin T.

    CHEMINFORM, Issue 7 2008
    Shyh-Ming Yang
    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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    ChemInform Abstract: Synthesis of ,-Hydroxybutenolides Applying Crossed Aldol Condensation in the Presence of a Bulky Lewis Acid and Their Antitumor Activity.

    CHEMINFORM, Issue 6 2008
    Yumiko Yamano
    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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    Lewis Acid Promoted Direct Substitution of 2-Methoxy-3-cyanopyridines by Organo Cuprates.

    CHEMINFORM, Issue 31 2007
    Part 3.
    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. [source]

    Reductive Mannich-Type Reaction Using the Composite Reagents of Phosphine and Lewis Acid.

    CHEMINFORM, Issue 26 2006
    Satoshi Kikuchi
    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. [source]

    Lewis Acid Assisted Cross Metathesis of Acrylonitrile with Functionalized Olefins Catalyzed by Phosphine-Free Ruthenium Carbene Complex.

    CHEMINFORM, Issue 11 2006
    Chen-Xi Bai
    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. [source]

    Ionic Liquid [omim][PF6] as an Efficient and Recyclable Reaction Media for the Cyanosilylation of Aldehydes Without Lewis Acid or Any Special Activation.

    CHEMINFORM, Issue 33 2005
    Zhi-Liang Shen
    Abstract For Abstract see ChemInform Abstract in Full Text. [source]

    Lewis Acid Promoted Annulation of o-Quinonediimines by Allylstannane: A Facile Synthesis of Quinoxaline Derivatives.

    CHEMINFORM, Issue 12 2005
    Vijay Nair
    Abstract For Abstract see ChemInform Abstract in Full Text. [source]

    Chemoselective Cyclizations of Divinyl Ketones to Cyclohexenones Mediated by Lewis Acid and Base.

    CHEMINFORM, Issue 52 2004
    Nabi A. Magomedov
    Abstract For Abstract see ChemInform Abstract in Full Text. [source]

    Stereoselective Synthesis of Functionalized Triol Units by SnCl4 Promoted Allylation of ,-Benzyloxyaldehydes: Crucial Role of the Stoichiometry of the Lewis Acid.

    CHEMINFORM, Issue 49 2004
    Christophe Dubost
    Abstract For Abstract see ChemInform Abstract in Full Text. [source]

    Lewis Acid Promoted Aldol Reaction of Fluorinated Silyl Enol Ethers from New Fluoroacetylsilane Derivatives.

    CHEMINFORM, Issue 42 2004
    Woo Jin Chung
    Abstract For Abstract see ChemInform Abstract in Full Text. [source]

    Lewis Acid Promoted Cyclization of Heteroatom-Substituted Enynes.

    CHEMINFORM, Issue 22 2004
    Shoko Yamazaki
    Abstract For Abstract see ChemInform Abstract in Full Text. [source]

    Cobalt-Catalyzed Photolytic Methoxycarbonylation of Bromoalkanes in the Presence of a Lewis Acid.

    CHEMINFORM, Issue 19 2004
    Daniel Cash
    Abstract For Abstract see ChemInform Abstract in Full Text. [source]