<i>In‐situ</i> Generated and Premade 1‐Copper(I) Alkynes in Cycloadditions

Wang, Xinyan; Wang, Xingyong; Wang, Xuesong; Zhang, Jianlan; Liu, Chulong; Hu, Yuefei

doi:10.1002/tcr.201700011

Cited by 11 publications

(9 citation statements)

References 148 publications

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“…Standard procedure starting from copper(I) acetylide ( Scheme ) . In a 50‐mL round‐bottom flask with a stirring bar, copper(I) acetylide (0.5 mmol) was dissolved in MeOH (1.0 mL). The flask was purged with oxygen and sealed with a rubber septum.…”

Section: Methodsmentioning

confidence: 99%

Cu^II‐Catalyzed Oxidative Formation of 5‐Alkynyltriazoles

Liu

Brassard

Lee

et al. 2020

Chemistry An Asian Journal

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In an alcoholic solventu nder the catalysis of Cu(OAc) 2 ·H 2 O, organic azide and terminal alkyne could oxidatively couple to afford 5-alkynyl-1,2,3-triazole (alkynyltriazole) at room temperature under an atmosphere of O 2 in a few hours. The involvemento f1 ,5-diazabicyclo[4.3.0]non-5ene (DBN) is essential, withoutw hich the redoxn eutral coupling insteadp roceeds to produce 5-H-1,2,3-triazole (protiotriazole) as the major product. Therefore, DBN switches the redox neutralc oupling between terminal alkyne and organic azide, the copper-catalyzed "click" reaction to afford protio-triazole, to an oxidation reaction that resultsi na lkynyltriazole. The organic base DBN is effective in accelerating the copper(II)-catalyzed oxidation of terminal alkyne or copper(I) acetylide, whichi si ntercepted by an organic azide to produce alkynyltriazole. The proposed mechanistic model suggests that the selectivity between alkynyl-and protiotriazole, and other acetylide or triazolide oxidation products is determined by the competition between copper(I)-catalyzed redox neutral cycloadditiona nd copper(II)/O 2 -mediated acetylide oxidation after the formationo fc opper(I) acetylide.Scheme1.Copper-catalyzed azide-alkyne cycloaddition under redox neutral or oxidative conditions( [a] TBTA = tris[(1-benzyl-1H-1,2,3-triazol-4-yl)methyl]amine, al igand known for accelerating copper-catalyzed triazole ring formation from azide and terminalalkyne. [5] ).

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Section: Methodsmentioning

confidence: 99%

Cu^II‐Catalyzed Oxidative Formation of 5‐Alkynyltriazoles

Liu

Brassard

Lee

et al. 2020

Chemistry An Asian Journal

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“…The cycloaddition of the azide to the alkyne occurred in a single concerted step (rather than a stepwise step). In a carboxylic acid-promoted CuAAC reaction developed by Hu and co-workers, the roles of acetic acid in the cycloaddition and protonation steps in the CuAAC reaction were verified by density functional theory (DFT) calculations by Tüzün and co-workers …”

Section: Introductionmentioning

confidence: 94%

“…When the reaction occurred in the binuclear mode, a π, σ-bis(copper) acetylide reactive species was involved (Scheme b). The introduction of a second copper ion into the metallacycle structure decreased the activation barrier of dicopper metallacycle species formation, promoting the formation of triazole in a kinetically more favored way. − The bis–copper complexes have been verified by experiments, ,− and the binuclear mechanism in the CuAAC reaction was supported by the computational investigations. − ,− The ligand in dicopper complexes or additives in the reaction might prevent the polymerization of the in situ generated 1-copper(I) alkynes, stabilize the Cu(I) center to avoid deactivation (e.g., oxidation and disproportionation), and even change the reaction mechanism in some cases . Héron and Balcells studied the mechanism of the CuAAC reaction catalyzed by 1,8-naphthyridine dicopper complexes with two different metal-coordinating substituents [i.e., −P( t Bu) 2 and −C(Me) (Py) 2 ] using the PBE0 functional.…”

Section: Introductionmentioning

confidence: 97%

Theoretical Study on Cooperation Catalysis of Chiral Guanidine/ Copper(I) in Asymmetric Azide–Alkyne Cycloaddition/[2 + 2] Cascade Reaction

Wei

Zhang

et al. 2023

J. Org. Chem.

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Density functional theory (DFT) calculations with BP86-D3(BJ) functionals were employed to reveal the mechanism and stereoselectivity of chiral guanidine/copper(I) salt-catalyzed stereoselective three-component reaction among N-sulfonyl azide, terminal alkyne, and isatin-imine for spiroazetidinimines that was first reported by Feng and Liu (Angew. Chem. Int. Ed. 2018, 57, 16852−16856). For the noncatalytic cascade reaction, the denitrogenation to generate ketenimine species was the ratedetermining step, with an activation barrier of 25.8−34.8 kcal mol −1 . Chiral guanidine-amide promoted the deprotonation of phenylacetylene, generating guanidine-Cu(I) acetylide complexes as active species. In azide−alkyne cycloaddition, copper acetylene coordinated to the O atom of the amide moiety in guanidium, and TsN 3 was activated by hydrogen bonding, affording the Cu(I)ketenimine species with an energy barrier of 3.5∼9.4 kcal mol −1 . The optically active spiroazetidinimine oxindole was constructed via a stepwise four-membered ring formation, followed by deprotonation of guanidium moieties for C−H bonding in a stereoselective way. The steric effect of the bulky CHPh 2 group and chiral backbone in the guanidine, combined with the coordination between the Boc group in isatin-imine with a copper center, played important roles in controlling the stereoselectivity of the reaction. The major spiroazetidinimine oxindole product with an SS configuration was formed in a kinetically more favored way, which was consistent with the experimental observation.

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“…We realized that the “bare” 1-copper(I) alkynes may meet this purpose. It is well-known that most 1-copper(I) alkynes have polymeric structures as (RCCCu) n in which each alkyne and Cu(I) coordinate each other by three C–Cu bonds. Since there are no exogeneous ligands, these “bare” 1-copper(I) alkynes are represented by a simple formula RCCCu.…”

mentioning

confidence: 99%

“…They can be prepared as air-stable microcrystallines within 1 h and stored at room temperature for many years. In the past decade, 1-copper(I) alkynes have been widely used in organic synthesis − including some works from our group. ,, Thus, we were encouraged to test a group of conditional reactions between amides ( 4a – 4c and 2a ) and copper(I) phenylethyne ( 3a ). As shown in Scheme a, no reaction occurred when the aryl amides 4a – 4c were treated by Tf 2 O and the yellow solid 3a was recovered in almost quantitative yield (before the hydrolysis).…”

mentioning

confidence: 99%