Copper-Catalyzed Reaction of Terminal Alkynes with Nitrones. Selective Synthesis of 1-Aza-1-buten-3-yne and 2-Azetidinone Derivatives

Miura, Masahiro; Enna, Masahiro; Okuro, Kazumi; Nomura, Masakatsu

doi:10.1021/jo00121a018

Cited by 287 publications

(136 citation statements)

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“…[145] This so-called Kinugasa reaction [146] had first been described as early as 1972 and was later adapted to proceed with terminal alkynes in the presence of substoichiometric amounts of copper(I) iodide (Scheme 61, upper part). [147] Recently, various asymmetric variants of this reaction have been presented by the groups of Basak, [148] Tang [149] and Fu.…”

Section: Scope and Applicabilitymentioning

confidence: 99%

Highly Active Dinuclear Copper Catalysts for Homogeneous Azide–Alkyne Cycloadditions

et al. 2012

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It is better to light a candle than to curse the dark. AbstractThe copper-catalyzed azide-alkyne cycloaddition for the synthesis of 1,4-disubstituted 1,2,3-triazoles (CuAAC) is a variant of Huisgen's 1,3-dipolar cycloaddition which disburdens the thermal reaction from its major drawbacks such as poor regioselectivity, long reaction times and harsh conditions. In contrast to the widely used "black box" reagent mixtures, a molecularly defined, highly active catalyst system for homogeneous CuAAC reactions has been developed in this PhD project. In dependence on the postulated stepwise mechanism, its most important structural feature is the presence of two copper(I) ions irreversibly bound in the same catalyst molecule.A highly modular and profitable synthesis for bistriazolium hexafluorophosphate salts as precursors for the ancillary ligand system was devised. In analogy to the CuAAC catalyst systems of general formula [(NHC) 2 Cu]PF 6 described in literature, novel dinuclear copper(I) complexes with a bistriazolylidene ligand backbone and 1,3-bis(2,6-diisopropylphenyl)-imidazol-2-ylidene (IPr) as sacrificial ligand were prepared.However, these complexes did not show the expected high catalytic activity, most probably due to the strong coordination of the IPr ligands. In consequence, another family of dinuclear copper(I) complexes with m-coordinated acetate as labile ligand was synthesized by reaction of the bistriazolium hexafluorophosphate ligand precursors with copper(I) acetate in the presence of a base.The broad applicability and high catalytic activity of one of these bistriazolylidene dicopper acetate complexes was confirmed by a series of gaschromatographically mo-

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Section: Scope and Applicabilitymentioning

confidence: 99%

Highly Active Dinuclear Copper Catalysts for Homogeneous Azide–Alkyne Cycloadditions

et al. 2012

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“…We then switched our efforts to other transition metals, such as Zn(II), Cu(I)͞(II), Ir(I), and Sc(III) ( Table 1), some of which have been reported to lead the formation of metal alkynilides (33)(34)(35)(36)(37)(38)(39)(40)(41). In the investigation of 4-phenyl-1-butyne 2a addition to ␣-imino ester 1, none of the target was essentially detected in the presence of IrCl⅐2COD, Zn(OTf) 2 , ZnCl 2 , and Sc(OTf) 3 (entry 1).…”

Section: Resultsmentioning

confidence: 99%

Catalytic asymmetric alkynylation of α-imino ester: A versatile approach to optically active unnatural α-amino acid derivatives

Chan

2005

Proc. Natl. Acad. Sci. U.S.A.

104

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The catalytic asymmetric introduction of alkynyl functionality to ␣-amino acid derivatives was realized by the direct addition of terminal alkynes to ␣-imino ester in the presence of chiral Cu(I) complex under mild reaction conditions. Owing to the rich chemistry to which alkyne can be subjected, the present system provides a remarkably versatile tool for the construction of optically active ␣-amino acid derivatives. Good yields and enantiomeric excess values were achieved with an array of terminal alkynes and challenging, biologically active, unnatural ␣-amino acid derivatives could be conveniently obtained. asymmetric catalysis Optically active nonproteinogenic ␣-amino acids are of exceptional and rapidly increasing popularity as important tools in protein engineering and peptide-based drug discovery due mainly to their implementation into nonscissile peptide mimics and peptide isosteres (1-7). Hence, intense research has been focused on the preparation of enantiomerically enriched unnatural ␣-amino acids, and, so far, several approaches, such as bioresolution routes (8-10) and the rhodium-or rutheniumcatalyzed asymmetric hydrogenation of dehydroamino acids derivatives (11-13), have shown much promise. Nevertheless, there is still a great demand for more efficient and, especially, technically feasible methods for convenient construction of various types of rational designed unnatural amino acid derivatives. In this regard, enantioselective nucleophilic addition to ␣-imino esters represents one of the most direct strategies (14), because a new chiral center and a new COC bond can be built in a single operation and an appropriately designed side chain can be introduced in the meantime. Previous work in this field mainly focused on the catalytic asymmetric alkylation of ␣-imino esters, in which enol silane (15-18), allyl-metal compounds (19,20), trimethylsilyl nitronate (21), ketone (22), and nitroalkane (23) have been used as nucleophiles.Recently, we reported the successful alkynylation of ␣-imino ester by demonstrating the feasibility of direct addition of terminal alkynes to ␣-imino ester 1 in the presence of Ag(I) salts under mild reaction conditions (Scheme 1) (24). In this process, a new bond between an sp 3 carbon and an sp carbon is formed.Capitalizing on this method, we envisioned an attractive route to optically active ␣-amino acid derivatives via the direct asymmetric alkynylation of ␣-imino ester. The following considerations are particularly noteworthy:1. The HC'C moiety is an excellent two-carbon medium for the delivery of biologically interesting units into the ␥-position of ␣-amino acids, because it could be easily hydrogenated to saturated status after completing the nucleophile role. In contrast, owing to the rich chemistry to which alkyne can be subjected, the presence of a C'C bond in the desired targets offers a unique and highly valuable opportunity for further synthetic elaboration on the ␤,␥-positions of ␣-amino acids. For example, semireduction of the products could directly afford vinyl...

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“…Further, direct addition of terminal alkynes to aldehydes was reported by Yamaguchi et al [73], Han and Huang [74], and Carreira et al [75]. For the addition of terminal alkynes to C=N bonds, Miura et al reported the addition of acetylene to nitrones through the initial formation of a dipolar cycloaddition [76], while Carreira and co-workers used a Zn(II)-catalyzed process in CH 2 Cl 2 for the addition of terminal alkynes to nitrones [77].…”

Section: Nucleophilic Addition Of Terminal Alkynes In Watermentioning

confidence: 92%

Synthetic Chemistry with an Eye on Future Sustainability

Deng

Sheldon

et al. 2012

Organic Chemistry – Breakthroughs and Perspectives

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Copper-Catalyzed Reaction of Terminal Alkynes with Nitrones. Selective Synthesis of 1-Aza-1-buten-3-yne and 2-Azetidinone Derivatives

Cited by 287 publications

References 0 publications

Highly Active Dinuclear Copper Catalysts for Homogeneous Azide–Alkyne Cycloadditions

Highly Active Dinuclear Copper Catalysts for Homogeneous Azide–Alkyne Cycloadditions

Catalytic asymmetric alkynylation of α-imino ester: A versatile approach to optically active unnatural α-amino acid derivatives

Synthetic Chemistry with an Eye on Future Sustainability

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