ChemInform Abstract: Enantioselective C‐C Bond Formation with Chiral Lewis Acids.

Reetz, Manfred T.; Kyung, Suk‐Hun; Bolm, Carsten; Zierke, Thomas

doi:10.1002/chin.198719082

Cited by 27 publications

(36 citation statements)

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“…Of particular interest are those complexes derived from an enantiomerically pure chelating diol. Thus, [TiCl 2 (BINOLato)] complexes (BINOLato [1,1'-binaphthalene]-2,2'-diolato(2 À)-kO,kO') have found specific use in enantioselective Mukaiyama aldol reactions [2], cyanosilylation of aldehydes [2], carbonyl-ene reactions [3], carbonyl allylsilane or allylstannane additions [4 ± 6], ene cyclizations [7], (hetero)-Diels-Alder reactions [8], and others (for a review, see [9]). Complexes of the type [TiCl 2 (TADDOLato)] 1 ) serve as catalysts in enantioselective cyanosilylations [10], (hetero)-Diels-Alder [11 ± 15], [2 2] cycloadditions [16 ± 18], [2 3] cycloadditions [19], 1,3-dipolar cycloadditions [20], nitro-aldol reactions [21], fluorinations [22], and others (for reviews, see [9] [23]).…”

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confidence: 99%

TitaniumLewis Acids for Asymmetric Catalysis: Synthesis and Structural Characterization of Dichloro[diolato(2−)-κO,κO′]bis(solvent)titanium ([TiCl2(diolato)(solvent)2]) Complexes

Hintermann

Broggini

Togni

2002

HCA

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The complexes [TiCl 2 {(R,R)-TADDOLato}(DME)] ¥ MeCN (3), and [TiCl 2 {(R,R)-1-Nph-TADDOLato}(MeCN) 2 ] ¥ CH 2 Cl 2 (4b) (DME 1,2-dimethoxyethane; (R,R)-TADDOLato (4R,5R)-2,2-dimethyla,a,a',a'-tetraphenyl-1,3-dioxolane-4,5-dimethanolato(2 À)-kO,kO';(R,R)-1-Nph-TADDOLato (4R,5R)-2,2-dimethyl-a,a,a',a'-tetra(naphthalen-1-yl)-1,3-dioxolane-4,5-dimethanolato(2 À)-kO,kO') were prepared and isolated in high yield as stable crystalline materials (Scheme 1). They constitute ideally suited and easyto-handle catalyst precursors for a large number of Ti-catalyzed asymmetric reactions, for which they have been previously generated in situ. The X-ray crystal structures of 3 and 4b show a distorted octahedral geometry around Ti with the chloro ligands in mutual trans positions (Figs. 5 and 6). The new chiral diols a-(1S,3R)-3-hydroxy-2,2,3-trimethylcyclopentyl]-a-phenylbenzenemethanol (13a), derived from camphoric acid (5), and (M)-6,6'-dimethyl-a,a,a',a'-tetraphenyl[1,1'-biphenyl]-2,2'-dimethanol (15) were prepared (Schemes 3 and 4). These new ligands are able to form mononuclear complexes with the Ti IV Cl 2 fragment. The corresponding complex 14 derived from 13a was characterized by X-ray as a mixed THF/MeCN adduct. 1. Introduction. ± Complexes of the general formula [TiCl 2 (OR) 2 ] serve as Lewis acid catalysts or mediators (i.e., in stoichiometric amounts) in allylation reactions of aldehydes in the presence of allylstannanes, hetero-Diels-Alder reactions, ene reactions, Michael additions, Mukaiyama silyl-aldol condensations, and other reactions (see review [1]). Of particular interest are those complexes derived from an enantiomerically pure chelating diol. Thus, [TiCl 2 (BINOLato)] complexes (BINOLato [1,1'-binaphthalene]-2,2'-diolato(2 À)-kO,kO') have found specific use in enantioselective Mukaiyama aldol reactions [2], cyanosilylation of aldehydes [2], carbonyl-ene reactions [3], carbonyl allylsilane or allylstannane additions [4 ± 6], ene cyclizations [7], (hetero)-Diels-Alder reactions [8], and others (for a review, see [9]). Complexes of the type [TiCl 2 (TADDOLato)] 1 ) serve as catalysts in enantioselective cyanosilylations [10], (hetero)-Diels-Alder [11 ± 15], [2 2] cycloadditions [16 ± 18], [2 3] cycloadditions [19], 1,3-dipolar cycloadditions [20], nitro-aldol reactions [21], fluorinations [22], and others (for reviews, see [9] [23]).When inspecting the procedures for the generation of the titanium catalysts used in the reactions mentioned above, one notes that they are prepared in situ according to

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confidence: 99%

TitaniumLewis Acids for Asymmetric Catalysis: Synthesis and Structural Characterization of Dichloro[diolato(2−)-κO,κO′]bis(solvent)titanium ([TiCl2(diolato)(solvent)2]) Complexes

Hintermann

Broggini

Togni

2002

HCA

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“…This catalyst resulted in moderate induction with several aldehydes including the three shown in Sch. 6 Asymmetric induction was found not to be dependent on catalyst loading. For example, addition to cyclohexane carboxaldehyde occurred with 56 YO ee whether 100 or 10 mol YO catalyst was used, although the reaction was slower for the latter, proceeding in 17 h rather than 0.5 h. Several other ligands were evaluated for this reaction and it was found that ligand 48, derived from the cyclohexyl amide of valine was optimal in terms of rate and asymmetric induction.…”

Section: Carbonyl Additions and Reductionsmentioning

confidence: 97%

“…The earliest such carbonyl addition reaction to be reported was, along with the Muikaiyama aldol reaction of ketene acetal7 (Sch. 2), the addition of trimethylsilyl cyanide to iso-valeraldehyde [6]. The catalyst 13 did not result in asymmetric induction as high in this reaction as it did with the Muikaiyama aldol reaction of ketene acetal 7 with iso-valeraldehyde (Sch.…”

Section: Carbonyl Additions and Reductionsmentioning

confidence: 99%

Chiral Aluminum Lewis Acids in Organic Synthesis

Wulff

2000

Lewis Acids in Organic Synthesis

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The earliest report of a reaction mediated by a chiral three coordinate aluminum species describes an asymmetric Meerwein-Ponndorf-Verley reduction of ketones with chiral aluminum alkoxides which resulted in low induction in the alcohol products [1]. Subsequent developments in the area were sparse until over a decade later when chiral aluminum Lewis acids began to be explored in polymerization reactions, with the first report describing the polymerization of benzofuran with catalysts prepared from and ethylaluminum dichloride and a variety of chiral compounds including /3-phenylalanine [2]. Curiously, these reports did not precipitate further studies at the time because the next development in the field did not occur until nearly two decades later when Hashimoto, Komeshima and Koga reported that a catalyst derived from ethylaluminum dichloride and menthol catalyzed the asymmetric Diels-Alder reaction shown in Sch. 1 [3,4]. This is especially curious because the discovery that a Diels-Alder reaction could be accelerated by aluminum chloride was known at the time the polymerization work appeared [5]. Perhaps it was because of this long delay, that the report of this asymmetric catalytic Diels-Alder reaction was to become the inspiration for the dramatic increase in activity in this field that we have witnessed in the twenty years since its appearance. It is the intent of this review to present the development of the field of asymmetric catalytic synthesis with chiral aluminum Lewis acids that includes those reports that have appeared in the literature up to the end of 1998. This review will not cover polymerization reactions or supported reactions. The latter will appear in a separate chapter in this handbook. 15 rnol % catalyst 4 toluene, -78 OC, 3 h 0 2 1.1 equiv 3 69 % yield exo : endo = 98 : 2 72 % ee 1 EtAlC12 . OAIC12 A A 5 4 Scheme 1

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“…Catalytic asymmetric aldol reaction involving ligands possessing symmetry elements of pure rotation such as BINOL and derivatives have been extensively studied. Reetz et al 36 firstly reported enantioselective Mukaiyama aldol reactions involving BINOL-Ti(IV) complex as Lewis acid.…”

Section: Binol and Related Ligands In Catalytic Stereoselective Mukaimentioning

confidence: 99%

Metal-catalyzed asymmetric aldol reactions

Dias¹,

Lucca²,

Ferreira³

et al. 2012

J. Braz. Chem. Soc.

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A reação aldólica é uma das ferramentas mais poderosas e versáteis para a construção de ligações C−C. Tradicionalmente, esta reação foi desenvolvida em sua versão estequiométrica, no entanto, grandes esforços no desenvolvimento de catalisadores quirais para reações aldólicas foram realizados nos últimos anos. Desta forma, neste artigo de revisão, é discutido o desenvolvimento de catalisadores metálicos em reação aldólica do tipo Mukaiyama, reação aldólica redutiva e reação aldólica direta. Além disto, a aplicação destes catalisadores na síntese total de moléculas complexas será abordada.The aldol reaction is one of the most powerful and versatile methods for the construction of C−C bonds. Traditionally, this reaction was developed in a stoichiometric version; however, great efforts in the development of chiral catalysts for aldol reactions were performed in recent years. Thus, in this review article, the development of metal-mediated chiral catalysts in Mukaiyama-type aldol reaction, reductive aldol reaction and direct aldol reaction are discussed. Moreover, the application of these catalysts in the total synthesis of complex molecules is discussed.

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ChemInform Abstract: Enantioselective C‐C Bond Formation with Chiral Lewis Acids.

Abstract: The preparation of chiral Lewis acids (I) ‐ (III) which have bidentate ligands is described.

Cited by 27 publications

References 0 publications

TitaniumLewis Acids for Asymmetric Catalysis: Synthesis and Structural Characterization of Dichloro[diolato(2−)-κO,κO′]bis(solvent)titanium ([TiCl2(diolato)(solvent)2]) Complexes

TitaniumLewis Acids for Asymmetric Catalysis: Synthesis and Structural Characterization of Dichloro[diolato(2−)-κO,κO′]bis(solvent)titanium ([TiCl2(diolato)(solvent)2]) Complexes

Chiral Aluminum Lewis Acids in Organic Synthesis

Metal-catalyzed asymmetric aldol reactions

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