Copper-catalysed benzylic C–H coupling with alcohols via radical relay enabled by redox buffering

Hu, Huayou; Chen, Si Jie; Mandal, Mukunda; Pratik, Saied Md; Buss, Joshua A.; Krska, Shane W.; Cramer, Christopher J.; Stahl, Shannon S.

doi:10.1038/s41929-020-0425-1

Cited by 132 publications

(140 citation statements)

References 49 publications

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“…As the best-in-class anode in this work, the W 2 C/N 3.0 C electrode provides a high turnover frequency (TOF) value of 18.8 h -1 , which is comparable to or even higher than the reported values, mostly of homogeneous catalysts, for similar alkoxylation reactions ( Fig. 4c and Supplementary Table 3-5) 38,39 .…”

Section: Introductionsupporting

confidence: 64%

Electrochemical activation of C–H by electron-deficient W2C nanocrystals for simultaneous alkoxylation and hydrogen evolution

Lin

Zhang

et al. 2020

Preprint

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Activation of C − H bonds is maybe the central challenge in organic chemistry and usually the key step for the retro-synthesis of functional natural products and medicines from abundant hydrocarbons due to the high chemical stability of C − H bonds. Electrochemical methods are now recognized as a powerful alternative for C − H activation, but this approach usually requires high overpotential and homogeneous mediators. Here, we designed electron-deficient W2C nanocrystal-based electrodes to boost the heterogeneous activation of C − H bonds under mild conditions via an additive-free, purely heterogeneous electrocatalytic strategy. The electron density of W2C nanocrystals was tuned by constructing Schottky heterojunctions with nitrogen-doped carbon support to facilitate the preadsorption and activation of benzylic C − H bonds of ethylbenzene on the W2C surface, enabling a high turnover frequency (18.8 h− 1) at a comparably low work potential (2 V versus SCE). The pronounced electron deficiency of the W2C nanocatalysts substantially facilitates the direct deprotonation process to ensure long-term electrode durability without self-oxidation. The efficient oxidation process also boosts the balancing hydrogen production from as-formed protons on the cathode by a factor of 10 compared to an inert reference electrode. The whole process meets the requirements of atomic economy and electric energy utilization in terms of sustainable chemical synthesis.

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Section: Introductionsupporting

confidence: 64%

Electrochemical activation of C–H by electron-deficient W2C nanocrystals for simultaneous alkoxylation and hydrogen evolution

Lin

Zhang

et al. 2020

Preprint

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“…It is well known that a carbon‐centered radical can be stablized by heteroatoms adjacent to the radical such as nitrogen, [16] thus promoting us to survey the enantioselective enantioselective cyanation of CRAN generated by radical addition to enamides; in addition, a coordination of the carbonyl group in the enamide to a copper center woud be highly beneficial to the enantioselective induction (Scheme 1 b, ii ). Moreover, Stahl and co‐workers recently reported a copper‐catalyzed etherification of benzylic C−H bonds [17] . However, employing chiral Box ligand failed to achieve an enantioselective reaction, yielding racemic oxygenation products.…”

Section: Methodsmentioning

confidence: 99%

“…Moreover, Stahl and coworkers recently reported a copper-catalyzed etherification of benzylic CÀH bonds. [17] However, employing chiral Box ligand failed to achieve an enantioselective reaction, yielding racemic oxygenation products. The significantly different properties between CRAN and benzylic radicals also intrigued us to investigate the asymmetric coupling of CRAN to alcohols (Scheme 1 b, iii).…”

mentioning

confidence: 99%

Asymmetric Coupling of Carbon‐Centered Radicals Adjacent to Nitrogen: Copper‐Catalyzed Cyanation and Etherification of Enamides

Zhang

Zhou

et al. 2020

Angewandte Chemie

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The first copper-catalyzed asymmetric cyanation and etherification reactions of enamides have been established, where a carbon-centered radical adjacent to a nitrogen atom (CRAN) is enantioselectively trapped by a chiral copper(II) species. Moreover, the asymmetric cyanation of vinyl esters was disclosed as well. These reactions feature very mild reaction conditions and high functional group tolerance, and give a series of chiral a-cyano amides, a-cyano esters and ahemiaminals in good yields with excellent enantioselectivity. The chiral a-cyano amides can be easily converted into enantioenriched 1,2-diamines and amino acids. Scheme 1. Asymmetric radical difunctionalization of enamides.

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“…The catalytic system was applied to a broad scope of both alkylarenes and alcohols. 22 In 2015, the Su group described the esterification of non-activated (non-benzylic) and allylic Csp 3 -H bonds of hydrocarbons catalyzed by copper and with Selectfluor as the oxidant (Scheme 14a). A catalytic cycle based on the oxidation of the copper(II) salt and generation of a fluorinated copper(III) species was proposed (Scheme 14b).…”

Section: Scheme 11 Ritter-type C-h Amination Reactionmentioning

confidence: 99%

Recent Advances in Copper-Catalyzed Radical C–H Bond Activation Using N–F Reagents

Muñoz‐Molina¹,

Belderraín²,

Pérez

2020

Synthesis

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This Short Review is aimed at giving an update in the area of copper-catalyzed C–H functionalization involving nitrogen-centered radicals generated from substrates containing N–F bonds. These processes include intermolecular Csp3–H bond functionalization, remote Csp3–H bond functionalization via intramolecular hydrogen atom transfer (HAT), and Csp2–H bond functionalization, which might be of potential use in industrial applications in the future.1 Introduction2 Intermolecular Csp3–H Functionalization3 Remote Csp3–H Functionalization4 Csp2–H Functionalization5 Conclusion

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Copper-catalysed benzylic C–H coupling with alcohols via radical relay enabled by redox buffering

Cited by 132 publications

References 49 publications

Electrochemical activation of C–H by electron-deficient W2C nanocrystals for simultaneous alkoxylation and hydrogen evolution

Electrochemical activation of C–H by electron-deficient W2C nanocrystals for simultaneous alkoxylation and hydrogen evolution

Asymmetric Coupling of Carbon‐Centered Radicals Adjacent to Nitrogen: Copper‐Catalyzed Cyanation and Etherification of Enamides

Recent Advances in Copper-Catalyzed Radical C–H Bond Activation Using N–F Reagents

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