Convenient and Practical Alkynylation of Heteronucleophiles with Copper Acetylides

Theunissen, Cédric; Lecomte, Morgan; Jouvin, Kévin; Laouiti, Anouar; Guissart, Céline; Heimburger, Jérémy; Loire, Estelle; Evano, Gwilherm

doi:10.1055/s-0033-1341025

Cited by 24 publications

(3 citation statements)

References 4 publications

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“…Starting materials: UI3(THF)4, 71 U[N(SiMe3)2]3,72 and 1-H10 were prepared according to the reported procedures. Substituted copper(I) acetylide compounds were prepared according to the literature procedure to prepare copper (I) phenyl acetylide 73. Electrochemistry.…”

mentioning

confidence: 99%

¹³C NMR Shifts as an Indicator of U–C Bond Covalency in Uranium(VI) Acetylide Complexes: An Experimental and Computational Study

et al. 2019

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A series of uranium(VI)-acetylide complexes of the general formula, U VI (O)(C≡C-C6H4-R)[N(SiMe3)2]3, with variation of the para substituent (R = NMe2, OMe, Me, Ph, H, Cl) on the aryl(acetylide) ring, were prepared. These compounds were analyzed by 13 C NMR spectroscopy, which showed that the acetylide carbon bound to the uranium(VI) center, U-C≡C-Ar, was shifted strongly downfield, with δ(13 C) values ranging from 392.1 to 409.7 ppm for Cl and NMe2 substituted complexes, respectively. These extreme high-frequency 13 C resonances are attributed to large negative paramagnetic (σ para) and relativistic spin-orbit (σ SO) shielding contributions, associated with extensive U(5f) and C(2s) orbital contributions to the U−C bonding in title complexes. The trend in the 13 C chemical shift of the terminal acetylide carbon is opposite of that observed in the series of parent (aryl)acetylenes, due to shielding effects of the para substituent. The 13 C chemical shifts of the acetylide carbon instead correlate with DFT computed U-C bond lengths and corresponding QTAIM delocalization indices or Wiberg bond orders. SQUID magnetic susceptibility measurements were indicative of the Van Vleck temperature independent paramagnetism (TIP) of the uranium(VI) complexes, suggesting a magnetic fieldinduced mixing of the singlet ground-state (f 0) of the U(VI) ion with low-lying (thermally inaccessible) paramagnetic excited states (involved also in the perturbation-theoretical treatment of the unusually large paramagnetic and SO contributions to the 13 C shifts). Thus, together with reported data, we demonstrate the sensitive 13 C NMR shifts serve as a direct, simple and accessible measure of uranium(VI)-carbon bond covalency.

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confidence: 99%

¹³C NMR Shifts as an Indicator of U–C Bond Covalency in Uranium(VI) Acetylide Complexes: An Experimental and Computational Study

et al. 2019

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“…This fact prevents the application of these acetylides in aqueous media [52]. However, some acetylides, in particular acetylides of the coinage metals copper [53][54][55][56][57][58][59][60][61][62], silver [63][64][65][66][67], and gold [68][69][70][71][72][73], and of mercury [74,75] can be generated in water.…”

Section: Reaction Designmentioning

confidence: 99%

Direct Synthesis of C-Substituted [RC(O)CH2-CB11H11]− Carborate Anions

Barra,

Bernhardt,

Fellinger

et al. 2024

Inorganics

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A new synthetic method for the synthesis of C-substituted [RC(O)CH2-CB11H11]− carborate anions has been developed. The reaction of [closo-B11H11]2− with terminal alkynes in the presence of a copper catalyst leads to insertion into the boron cluster, and C-substituted [RC(O)CH2-CB11H11]− carborate anions are formed. These reactions are strongly dependent on the reaction conditions, the solvents, and the alkynes used. The alkynes HCCCO2Et, HCCCO2Me, and HCCCONH2 lead to the formation of [NH2C(O)CH2-CB11H11]− as the final product in aqueous ammonia solution. In contrast, the reaction using the alkyne HCCCOMe yields [MeC(O)CH2-CB11H11]−. The products have been fully characterized by multinuclear NMR and IR spectroscopy as well as mass spectrometry. The crystal structures of K[NH2C(O)CH2-CB11H11] and [NEt3CH2Cl][NH2C(O)CH2-CB11H11] have been determined.

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“…It is to be remembered that during optimization studies, the absence of base additive yielded a yellow precipitate which is consistent with copper(I) phenylacetylide (Table 1, entry 1). 45 As several oxidation states have been invoked for an intermediate of this sort, 46,47 further characterizations would possibly reveal their exact role in the catalytic cycle. Moreover, it is well known that copper(I) acetylide is the key intermediate for click reactions.…”

Section: Paper Synthesismentioning

confidence: 99%

Synthetic Access to 1,3-Butadiynes via Electro-redox Cuprous-Catalyzed Dehydrogenative Csp–Csp Homocoupling of Terminal Acetylenes

Kathiresan,

Praveen,

Krishnan

2023

Synthesis

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Herein, we disclose the oxidative homocoupling of terminal alkynes under electrochemically generated cuprous catalysis. The scope of this protocol was established by preparing an array of structurally and electronically different 1,3-butadiyne derivatives. Good synthetic yields, functional group tolerance, oxidant-free conditions, and no cross-selectivity are some of the intrinsic advantages of this methodology. The developed chemistry features the electro-redox formation of copper acetylide, an intermediate appropriate for the Csp–Csp coupling step. The chemical state of copper in the acetylide intermediate was found to be Cu(I), as confirmed by click trapping experiments, cyclic voltammetry, EPR spectroscopy, and XPS. A competition reaction to determine the reactivity of electronically dissimilar acetylenes revealed that the product ratio is rather dependent on the electronic nature of the alkynyl substituents. To highlight the synthetic value of the products, selected diynes were subjected to chemical diversification.

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Convenient and Practical Alkynylation of Heteronucleophiles with Copper Acetylides

Cited by 24 publications

References 4 publications

¹³C NMR Shifts as an Indicator of U–C Bond Covalency in Uranium(VI) Acetylide Complexes: An Experimental and Computational Study

¹³C NMR Shifts as an Indicator of U–C Bond Covalency in Uranium(VI) Acetylide Complexes: An Experimental and Computational Study

Direct Synthesis of C-Substituted [RC(O)CH2-CB11H11]− Carborate Anions

Synthetic Access to 1,3-Butadiynes via Electro-redox Cuprous-Catalyzed Dehydrogenative Csp–Csp Homocoupling of Terminal Acetylenes

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Convenient and Practical Alkynylation of Heteronucleophiles with Copper Acetylides

Cited by 24 publications

References 4 publications

13C NMR Shifts as an Indicator of U–C Bond Covalency in Uranium(VI) Acetylide Complexes: An Experimental and Computational Study

13C NMR Shifts as an Indicator of U–C Bond Covalency in Uranium(VI) Acetylide Complexes: An Experimental and Computational Study

Direct Synthesis of C-Substituted [RC(O)CH2-CB11H11]− Carborate Anions

Synthetic Access to 1,3-Butadiynes via Electro-redox Cuprous-Catalyzed Dehydrogenative Csp–Csp Homocoupling of Terminal Acetylenes

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¹³C NMR Shifts as an Indicator of U–C Bond Covalency in Uranium(VI) Acetylide Complexes: An Experimental and Computational Study

¹³C NMR Shifts as an Indicator of U–C Bond Covalency in Uranium(VI) Acetylide Complexes: An Experimental and Computational Study