Anion‐Induced Enantioselective Cyclization of Diynamides to Pyrrolidines Catalyzed by Cationic Gold Complexes

Mourad, A. K.; Leutzow, Juliane; Czekelius, Constantin

doi:10.1002/anie.201205416

Cited by 101 publications

(42 citation statements)

References 115 publications

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“…25−27 Notably, a gold(I)-catalyzed desymmetrization of dialkynyl tosylamides provides optically active 2-methylenepyrrolidines in a promising method. 28 In addition, an achiral Ag(I) complex catalyzes the desymmetrization of aminodiynes to racemic 1-pyrrolines in route to ± Monomorine I. 29 That is, the combination of highly enantioselective and diastereoselective hydroamination has not previously been realized in a desymmetrization reaction.…”

Section: ■ Introductionmentioning

confidence: 99%

Zirconium-Catalyzed Desymmetrization of Aminodialkenes and Aminodialkynes through Enantioselective Hydroamination

2015

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The catalytic addition of alkenes and amines (hydroamination) typically provides α-or β-amino stereocenters directly through C-N or C-H bond formation. Alternatively, desymmetrization reactions of symmetrical aminodialkenes or aminodialkynes provide access to stereogenic centers with the position controlled by the substrate's structure. In the present study of an enantioselective zirconium-catalyzed hydroamination, stereocenters resulting from C-N bond formation and desymmetrization of a prochiral quaternary center are independently controlled by the catalyst and reaction conditions. Using a single catalyst, the method provides selective access to either diastereomer of optically enriched five-, six-, and seven-membered cyclic amines from aminodialkenes and enantioselective synthesis of five-, six-, and seven-membered cyclic imines from aminodialkynes. Experiments on hydroamination of aminodialkenes testing the effects of the catalyst:substrate ratio, the absolute concentration of the catalyst, and the absolute initial concentration of the primary amine substrate show that the latter parameter strongly influences the stereoselectivity of the desymmetrization process, whereas the absolute configuration of the α-amino stereocenter generated by C-N bond formation is not affected by these parameters. Interestingly, isotopic substitution (H2NR vs D2NR) of the substrate enhances the stereoselectivity of the enantioselective and diastereoselective processes in aminodialkene cyclization and the peripheral stereocenter in aminodialkyne desymmetrization/cyclization. ABSTRACT: The catalytic addition of alkenes and amines (hydroamination) typically provides α-or β-amino stereocenters directly through C−N or C−H bond formation. Alternatively, desymmetrization reactions of symmetrical aminodialkenes or aminodialkynes provide access to stereogenic centers with the position controlled by the substrate's structure. In the present study of an enantioselective zirconium-catalyzed hydroamination, stereocenters resulting from C−N bond formation and desymmetrization of a prochiral quaternary center are independently controlled by the catalyst and reaction conditions. Using a single catalyst, the method provides selective access to either diastereomer of optically enriched five-, six-, and seven-membered cyclic amines from aminodialkenes and enantioselective synthesis of five-, six-, and seven-membered cyclic imines from aminodialkynes. Experiments on hydroamination of aminodialkenes testing the effects of the catalyst:substrate ratio, the absolute concentration of the catalyst, and the absolute initial concentration of the primary amine substrate show that the latter parameter strongly influences the stereoselectivity of the desymmetrization process, whereas the absolute configuration of the α-amino stereocenter generated by C−N bond formation is not affected by these parameters. Interestingly, isotopic substitution (H 2 NR vs D 2 NR) of the substrate enhances the stereoselectivity of the enantioselective and diastereoselecti...

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Section: ■ Introductionmentioning

confidence: 99%

Zirconium-Catalyzed Desymmetrization of Aminodialkenes and Aminodialkynes through Enantioselective Hydroamination

2015

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“…To address this problem, both well-defined large chiral ligands [5] and the use of chiral counter anions have been studied with some success. [6] Some of these reactions were rendered enantioselective by using other carbophilic catalysts, such as iridium, [7] platinum, [5c,8] palladium, [9] and copper. [10] However, these strategies can only be applied to a limited number of transformations.…”

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confidence: 99%

Enantioselective Tandem Cyclization of Alkyne‐Tethered Indoles Using Cooperative Silver(I)/Chiral Phosphoric Acid Catalysis

Zhu

Wang

et al. 2017

Angew Chem Int Ed

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We report the enantioselective synthesis of tetracyclic indolines using cooperative silver(I) and chiral phosphoric acid catalysis. A variety of alkyne-tethered indoles are suitable for this process. Mechanistic studies suggest that the in situ-generated silver(I) chiral phosphate activates both the alkyne and the indole nucleophile in the initial cyclization step through an intermolecular hydrogen bond and the phosphate anion promotes proton transfer. In addition, further modifications of the cyclization products enabled stereochemistry-function studies of a series of bioactive indolines.

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“…Several other chiral bis(tetrahydroisoquinoline)-derived carbene ligands were also reported to give modest enantioselectivity [83]. A breakthrough came about in 2012 through the use of a chiral phosphate counteranion-based catalyst system, allowing for high levels of enantioinduction to be achieved (Scheme 18) [84]. A summary of these and related studies has been published [85].…”

Section: Intramolecular Cyclizationsmentioning

confidence: 98%

Enantioselective Gold-Catalyzed Synthesis of Heterocyclic Compounds

Miles

Toste

2015

Topics in Heterocyclic Chemistry

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Asymmetric gold-catalyzed syntheses of a diverse range of heterocycles are described herein. This chapter outlines efforts toward the construction of these molecules via intermolecular, intramolecular, and tandem cyclization strategies. Additionally, asymmetric hydrogenation and epoxidation approaches are detailed. These methodologies generally utilize substrates containing soft, unsaturated carbon-carbon bonds, which can easily interact with the carbophilic gold atom(s). Mostly through the use of bis-or monophosphine ligands, modest to excellent yields and enantioselectivities are obtained for a variety of partially and fully saturated heterocycles. Although steric variation of the phosphine catalyst is the most commonly used strategy for enantioinduction, the use of chiral counteranions has proven useful for more challenging transformations. This chapter includes only examples of syntheses where a chiral gold catalyst is used in the direct formation of the heterocycle; examples of pendant functionalization of an existing heterocycle or chirality transfer from enantioenriched substrate to product are not included.

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Anion‐Induced Enantioselective Cyclization of Diynamides to Pyrrolidines Catalyzed by Cationic Gold Complexes

Cited by 101 publications

References 115 publications

Zirconium-Catalyzed Desymmetrization of Aminodialkenes and Aminodialkynes through Enantioselective Hydroamination

Zirconium-Catalyzed Desymmetrization of Aminodialkenes and Aminodialkynes through Enantioselective Hydroamination

Enantioselective Tandem Cyclization of Alkyne‐Tethered Indoles Using Cooperative Silver(I)/Chiral Phosphoric Acid Catalysis

Enantioselective Gold-Catalyzed Synthesis of Heterocyclic Compounds

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