Paired Electrocatalysis Unlocks Cross-Dehydrogenative Coupling of C(sp3)-H Bonds Using A Pentacoordinated Cobalt-Salen Catalyst

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Paired Electrocatalysis Unlocks Cross-Dehydrogenative Coupling of C(sp³)-H Bonds Using A Pentacoordinated Cobalt-Salen Catalyst

https://doi.org/10.21203/rs.3.rs-3816848/v1

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Cross-dehydrogenative coupling (CDC) of C(sp³)-H bonds is an ideal approach for C(sp³)-C(sp³) bonds construction. However, conventional approaches mainly rely on the single activation mode by either stoichiometric oxidants or electrochemical oxidation, which would lead to inferior selectivity in the reaction between similar C(sp³)-H bonds. We herein developed a paired electrocatalysis strategy to access an unconventional selectivity in the CDC of alcoholic α C(sp³)-H with allylic (or benzylic) C-H bonds, which combines hydrogen evolution reaction (HER) catalysis with hydride transfer (H^-T) catalysis. To maximize the synergistic effect of the catalyst combinations, a novel HER catalyst pentacoordinated Co-salen was disclosed, and it displayed a large redox-potential gap (1.98 V) and suitable redox potential. With the optimized catalyst combination, an electrochemical CDC protocol features an unconventional chemoselectivity (C-C vs. C-O coupling), excellent functional group tolerance (83 examples), useful byproduct (hydrogen), high regio- and site-selectivity. A plausible reaction mechanism was also proposed to rationalize the experimental observations.

Physical sciences/Chemistry/Organic chemistry/Synthetic chemistry methodology

Physical sciences/Chemistry/Electrochemistry/Electrocatalysis

The development of approaches forming C(sp³)−C(sp³) bonds is a central topic in organic synthesis.^1-5 A strategy based on cross-dehydrogenative coupling (CDC) is first unveiled by Li,^6-8 and it has been demonstrated as robust and general tool for the construction of C(sp³)−C(sp³) bonds with hydrogen as the only byproduct. Conventional CDC approaches commonly involve stoichiometric oxidants and high temperature (Fig. 1a), which would result in some selectivity issues including overoxidation, side reaction and undesired chemoselectivity. With the significant progress of synthetic electrochemistry,^9-19 it offers alternative choices^20-23 for the redox chemistry by directly manipulating electron transfer between substrates and electrodes. Consequently, impressive breakthrough has been achieved in the electrochemical CDC^24-25. However, most of the electrochemical CDC approaches only involve the activation of anodic oxidation, and nucleophiles bearing reactive C(sp³)-H are commonly required (Fig. 1b). With a long-term interest in paired electrolysis,^26-29 we envisaged that merging anodic oxidation and cathodic reduction might enable a dual activation mode for the CDC reaction of unactivated C(sp³)-H bonds (Fig. 1c), which would otherwise be inaccessible either for the conventional CDC approach or electrochemical oxidative CDC.

The cross-dehydrogenative coupling alcohols with allylic and benzylic C-H bonds could serve as a general and direct approach upgrading simple alcohols to value-added ones. Nevertheless, previous reports for the transformation only afford C-O coupling products either with conventional^30-31 or electrooxidative³² protocol due to the mismatch reactivity of the substrates (Fig. 2a); O-H is more reactive than C-H bonds. To reverse the chemoselectivity in the reaction, we herein reported a paired electrocatalysis^33-36 strategy (Fig. 2b), which consists of a hydride transfer (H^-T) catalyst³⁷ and a hydrogen evolution reaction (HER) catalyst^38-47 enabling a dual activation mode for both substrates. In the paired electrocatalytic system, H^-T catalyst could selectively remove hydride from alcohols to form carbocations, while HER catalyst shifts the dissociation equilibrium of weak acidic C-H bonds to deliver hydrogen and carbanions, thus affording alkylated alcohols.

To establish an efficient paired electrocatalytic system, good compatibility of anodic and cathodic catalysts is the first concern. Active anodic and cathodic catalysts have opposite redox nature, and their mutual interference would result in deteriorated catalytic-efficiency. In this work, a novel pentacoordinated Co(II)-salen catalyst was demonstrated as a stable HER catalyst with a large redox potential gap and suitable oxidation potential. By cooperating with a common hydride transfer (H^-T) catalyst 2,2,6,6-tetramethylpiperidoxyl (TEMPO), the pentacoordinated Co(II)-salen catalyst unlocks an unconventionally chemoselective CDC reaction of alcohols with allylic and benzylic C-H bonds to open up a general platform upgrading alcohols (Fig. 2c). This paired electrocatalytic protocol features high chemo-, stereo- and regioselectivity, excellent functional-group tolerance (>80 examples) and mild conditions.

The evaluation of HER catalysts. To better understand the relationship of structure and redox property, we initially synthesized a series of Co (II)-salen^48–49 HER catalysts cat 1-cat 7 (Fig. 3a). The novel structure of pentacoordinated catalyst was unambiguously identified by the single crystal diffraction analysis of cat 1 (Fig. 3b),⁵⁰ and it shows that cobalt center is shielded by a roof-like nitrogen coordination site, which would significantly enhance its stability. Redox property of the catalysts was next explored to support the above speculation. We concluded all of the redox peaks of catalysts arising from the process of Co^III/Co^II and Co^II/Co^I (Fig. 3c). As expected, pentacoordinated catalysts (cat 1-cat 3, 1.98–1.92 V) have uniformly larger redox potential gap than that of the conventional catalysts cat 4-cat 7 (1.14–1.34 V). This result verifies that pentacoordinated Co-salen catalysts are more stable under oxidation and reduction compared with the tetracoordinated counterparts. Noteworthy, CF₃ group (cat 1) was found to significantly improve the oxidation potential of Co^II/Co^III with the most positive peak at -0.157 V (vs. Fc/Fc⁺). This redox property endows cat 1 good compatibility with the aforementioned cocatalyst TEMPO. Moreover, we also compared the anodic oxidation of cat 1 (-0.157 V) with that of TEMPO (0.195 V); the narrow potential difference⁵¹ made it possible using cat 1 to facilitate the oxidation TEMPO. Further cyclic voltammetry experiment mixing cat 1 with TEMPO confirms the above conclusion by detecting obvious increase of the anodic peak of cat 1 (Fig. 3d). Nevertheless, other cobalt catalysts failed to produce the same results when mixing with TEMPO. Taken together, cat 1 showed good compatibility with the H⁻T catalyst TEMPO. The synergistic effect of the catalyst combination was demonstrated by accelerating the catalytic cycle of TEMPO at lower anodic potential⁵², thereby obviating undesired overoxidation.

Reaction optimization. Encouraged by the redox property study, we next investigated the cross-coupling reaction between benzyl alcohol (1a) and allylbenzene (2a) with various catalyst combinations. We screened catalysts using Cs₂CO₃ as base additive, ⁿBu₄NClO₄ as electrolyte, DMF as solvent, graphite felt and copper plate as anode and cathode, respectively. As shown in the Table 1, a suitable catalyst combination is crucial for the reaction efficiency in terms of yields (Entry 1–10). The optimal catalyst combination was identified with cat 1 as HER catalyst and TEMPO as H^-T catalyst, and the desired C-C coupling product 3a was obtained in 85% yield with exclusive C-C coupling and isomerizing-selectivity. By comparing the yields arising from other catalyst combinations, we concluded that HER catalyst with larger potential gap and H^-T catalyst with lower oxidation peak would benefit the reaction performance. The necessity of both catalysts was also supported by the control experiments removing either of the catalysts (Entry 11–13). We also highlighted the superiority of this electrochemical protocol when compared to conventional CDC conditions (Entry 14, see Table S3 for details).

Exploration of Scope. With the optimal reaction conditions in hand, a wide range of substrates bearing weakly acidic C(sp³)-H were investigated to couple with benzyl alcohol 1a (Table 2). Initially, we examined a series of toluene derivatives, and the desired C-C coupling products (3b-3i) were obtained with moderate yield. Notably, bioactive amide and sulfonamide substrates (3e, 3h-3i) bearing reactive α C-H were well-tolerated. Moreover, diaryl ketone was also amenable to give the corresponding product 3f, which conventionally preferred to proceed a Pinacol coupling. To our delight, mixture of β-methylstyrene isomers can be directly used as substrate to afford corresponding products with high E/Z selectivity (3j, 3k). Subsequently, various allylbenzene derivatives were tested in the electrochemical protocol. Substrates with multiple double bonds (3l) or different substitution patterns (3m-3p) are all well-tolerated to deliver the desired products with exclusive isomerizing-selectivity and E/Z selectivity. The site-selectivity of the electrochemical approach was also demonstrated by the case of 3q, and more acidic C-H is favored in the reaction. This cross-coupling reaction also enabled a late-stage functionalization for the natural product Magnolol and Eugenol derived substrates (3r-3s). Specifically, both of the allyl groups underwent isomerization to give a mono-coupling product 3r. Additionally, we investigated the electronic effect (3t-3ac) and position of substituents (3ad-3af), fused ring (3ag-3ah) and heterocycle (3ai). Uniformly good yields were observed for the substrates, although thienyl group led to diminished E/Z selectivity. It is noteworthy that radical sensitive groups such as cyclopropyl (3o, 3w) and ortho-vinyl (3af) were untouched during the electrochemical transformation, ruling out the possible radical pathway. Finally, toluene, hexene and 4-phenyl-1-butene proved to be failed substrates in the reaction due to their less acidic C-H bonds.

To further demonstrate the generality of the electrochemical cross-coupling reaction, we next tested a broad range of alcohols (Table 3). In general, variations on the electronic property (3aj-3bf) and substitution pattern (3bg-3bp) of benzyl alcohols are well tolerated. Electron-deficient substrates (3ar-3ax) with higher oxidation potential proved to be less efficient compared with the electron-rich alcohols (3aj-3aq). The functional-group tolerance of this approach was highlighted by the cases of 3ay-3bd, which commonly cannot survive under conventional CDC conditions. Furthermore, site-selectivity favoring less-hindered benzylic C-H was observed in the substrates containing two hydroxyl groups (3be-3bf). Other aromatic (3bq-3bv), aliphatic (3bw-3ca), secondary (3cb-3cc) and bioactive molecule (amylcinnamyl alcohol, Adapalene) derived alcohols (3cd-3ce) were also found to be suitable substrates to afford corresponding products with synthetically useful yields. Alcohols bearing cyclopropyl group gave the desired products 3bw-3bx. None of the ring expansion byproduct was detected, further confirming an ionic pathway.

Applications in Synthesis. Having examined the reaction generality, we turned our attention to probe the utility of our electrochemical protocol with gram-scale reaction and derivatization of products (Fig. 4). Gratifyingly, scaling up the model reaction to gram-scale afforded product 3a in a satisfactory yield (70%) even with lower catalyst loading (Fig. 4a). The byproduct, that is, the hydrogen gas was successfully collected using a balloon and verified with GC. This result suggests that protocol not only provides a route for organic transformation but also enables an avenue for fuels. Using a simple solar cell as electricity supply largely maintained the reaction efficiency (Fig. 4b). Under acidic conditions, homoallylic alcohol 3l proceeded a facile dehydration to give a conjugated light-emitting molecule 4 (Fig. 4c), which displayed prominent luminescent properties both in solution and solid state with maximum emission peak at 493 nm. Additionally, bioactive tetrahydrofuran product 5 was also accessed in high yield via NIS initiated iodocyclization.

Mechanism investigation. To gain insight into the reaction mechanism, a series of cyclic voltametric experiment and control experiments were conducted (Fig. 5). First, the electrochemical properties of 1a and 2a were investigated (Fig. 5a-5b). As shown in Fig. 2A, 1a and 2a seem to be redox inert within the window of -2.5-2.5 V (vs. Fc/Fc⁺). After enlarging the range from − 0.5 to -2.5 V, a couple of small waves (10^− 6 ~ 10^− 5 A) were detected at -2.04 V, which were attributed to the hydrogen atom absorption and desorption process in HER (see Fig. S20 for GC detection of H₂). Moreover, their intensity increases with the concentration of 2a. These observations illustrate that both of substrates are relatively unactive in the absence of catalysts. Second, catalytic role of cat 1 and TEMPO was explored (Fig. 5c-5d). Treatment of cat 1 with excessive 2a led to significant increases of both cathodic peaks of 2a and Co^II/Co^I; this observation verifies the catalytic role of cat 1 in the HER of 2a. On the other hand, mixing TEMPO with benzyl alcohol 1a also resulted in an obvious catalytic current suggesting the catalysis of TEMPO in the oxidation of 1a. Third, we conducted control experiments to elucidate the necessity of both electrode reactions (Fig. 5e). In a divided cell, no desired coupling product 3a was observed (Eq (a)), while benzaldehyde and allylbenzene carbanion (see Fig. S26 for its UV-vis spectra) were detected in anodic and cathodic chamber, respectively. Further replacing TEMPO with stoichiometric oxidant 2,2,6,6-tetramethyl-1-oxopiperidinium tetrafluoroborate only afforded benzaldehyde (Eq (b)). These results exclude the mechanism which only relies on anodic oxidation. Kinetic isotope effect (KIE) study was also investigated with intramolecular competition and parallel experiment,⁵³ and it reveals that the oxidation of 1a is the rate-determining step (Eq (c)-(d)).

On the basis of the above experimental observations and related mechanism reports,^37,44–46 a plausible reaction mechanism was proposed (Fig. 5f). Under anodic oxidation, pentacoordinated Co^II-salen (cat 1) is first oxidized to Co^III species, which could subsequently initiate the oxidation of TEMPO via single electron transfer (SET). The in situ generated reactive species A abstracts a hydride from 1a to deliver cation C and regenerates a protonated TEMPO (B). Over the cathode surface, the dissociation of proton from weakly acidic C(sp³)-H is promoted by the Co^I species arising from cat 1, and isomerized carbanion D is simultaneously generated along with hydrogen byproduct. Direct reaction between C and D affords the dehydrogenative product 3a.

In summary, we develop a paired electrocatalysis strategy for an unconventionally chemoselective cross-dehydrogenative coupling of alcohols with allylic and benzylic C-H bonds. The paired electrocatalysis consisting of H^-T and HER catalysts enables a dual activation for alcohol and weakly acidic C-H substrates, respectively. The success of this strategy largely relies on a pentacoordinated Co^II-salen HER catalyst and it shows unmatched compatibility with H^-T catalyst owing to its large redox-potential gap and suitable oxidative property. With the novel catalyst combinations, unconventional C(sp³)-C(sp³) coupling products are readily accessed along with the clean fuel hydrogen. We believe that this paired electrocatalysis strategy would open up an appealing platform that merges synthetic chemistry with energy chemistry.

General procedure for electrochemical CDC reaction. An undivided cell was equipped with a magnet stirrer, copper plate (1.8 *1.5 cm²), graphite felt (1.8 *1.5 cm²), as cathode and anode, respectively (the electrolysis setup is shown in Fig. S22). The substrate benzyl alcohol (52 µL, 0.5 mmol), allylbenzene 2a (199 µL, 1.5 mmol), Cs₂CO₃ (31 mg, 0.1 mmol), cat 1 (10 mg, 0.025 mmol), TEMPO (16 mg, 0.1 mmol) and ⁿBu₄NClO₄ (341 mg, 1.0 mmol) were added to the solvent DMF (10 mL). The resulting mixture was allowed to stir and electrolyze under constant current condition (20 mA, J = 7.4 mA٠cm^-2) at 0°C for 4 hours. The reaction mixture was subsequently poured into water (100 mL) and extracted with ethyl acetate (40 mL × 3). The combined organic phases were washed with saturated brine solution (100 mL). The volatile solvent was then removed with a rotary evaporator, and the residue was purified by column chromatography (PE/ EA = 8/1–5/1, v/v) on silica gel to afford the desired product 3a (95 mg) in 85% yield.

Data Availability

All data supporting the findings of this study, including experimental details, spectroscopic characterization data for all compounds are available within the paper and its Supplementary Methods, or from the corresponding author upon reasonable request.

Acknowledgements

The authors are grateful to the National Natural Science Foundation of China (21702113 and 92061110), the Anhui University (S020318006/069 and S020118002/113), and the Anhui Provincial Natural Science Foundation (2108085Y05 and 2308085Y14) for their financial support.

Author Contributions

S.Z. and M.L. conceived the project, designed the experiments and wrote the manuscript. K.L., M.L., X.L. and M.Z. performed the experimental work. K.L. and M.L. contributed equally for this work. Refinement and analysis of single-crystal data was conducted by Y.Z. and W.F. All authors discussed the results and commented on the manuscript.

Competing Interests

The authors declare no competing interests.

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Supplementary information is available for this paper at www.nature.com/reprints.

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Corey, E. J. & Cheng, X. M. The Logic of Chemical Synthesis, pp. 1‒91(John Wiley & Sons,1989).
Zhang, S.-Y., Zhang, F.-M. & Tu, Y.-Q. Direct Sp³ α C–H activation and functionalization of alcohol and ether. Chem. Soc. Rev. 40, 1937–1949 (2011).
Chen, Z., Rong, M.-Y., Nie, J., Zhu, X.-F., Shi, B.-F. & Ma, J.-A. Catalytic alkylation of unactivated C(sp³)–H bonds for C(sp³)–C(sp³) bond formation. Chem. Soc. Rev. 48, 4921‒4942 (2019).
Pitre, S. P., Weires, N. A. & Overman, L. E. Forging C(sp³)–C(sp³) Bonds with Carbon-Centered Radicals in the Synthesis of Complex Molecules. J. Am. Chem. Soc. 141, 2800‒2813 (2019).
Lei, C. & Zhou, Q.Advances on Nickel-Catalyzed C(sp³)-C(sp³) Bond Formation. Acta Chim. Sinica.78, 1017‒1029 (2020).
Li, C.-J. Cross-Dehydrogenative Coupling (CDC): Exploring C−C Bond Formations beyond Functional Group Transformations. Acc. Chem. Res. 42, 335–344 (2009).
Girard, S. A., Knauber, T. & Li, C.-J. The Cross-Dehydrogenative Coupling of Csp³-H Bonds: A Versatile Strategy for C−C Bond Formations. Angew. Chem. Int. Ed. 53, 74–100 (2014).
Tian, T., Li, Z. & Li, C.-J. Cross-dehydrogenative coupling: a sustainable reaction for C–C bond formations. Green Chem. 23, 6789–6862 (2021).
Yan, M., Kawamata, Y. & Baran, P. S. Synthetic organic electrochemical methods since 2000: on the verge of a renaissance. Chem. Rev. 117, 13230–13319 (2017).
Jiang, Y., Xu, K. & Zeng, C.-C. Use of electrochemistry in the synthesis of heterocyclic structures. Chem. Rev. 118, 4485–4540 (2018).
Yoshida, J.-i., Shimizu, A. & R. Hayashi, Electrogenerated cationic reactive intermediates: the pool method and further advances. Chem. Rev. 118, 4702–4730 (2018).
Moeller, K. D. Using physical organic chemistry to shape the course of electrochemical reactions. Chem. Rev. 118, 4817–4833 (2018).
Waldvogel, S. R., Lips, S., Selt, M., Riehl, B. & Kampf, C. J. Electrochemical arylation reaction. Chem. Rev. 118, 6706–6765 (2018).
Yuan, Y. & Lei, A. Electrochemical oxidative cross-coupling with hydrogen evolution reactions. Acc. Chem. Res. 52, 3309–3324 (2019).
Xiong, P. & Xu, H.-C. Chemistry with electrochemically generated N-centered radicals. Acc. Chem. Res. 52, 3339–3350 (2019).
Jiao, K.-J., Xing, Y.-K., Yang, Q.-L., Qiu, H. & Mei, T.-S. Site-Selective C–H functionalization via synergistic use of electrochemistry and transition metal catalysis. Acc. Chem. Res. 53, 300–310 (2020).
Gandeepan, P., Finger, L. H., Meyer, T. H. & Ackermann, L. 3d metallaelectrocatalysis for resource economical syntheses. Chem. Soc. Rev. 49, 4254–4272 (2020).
Novaes, L. F. T., Liu, J., Shen, Y., Lu, L., Meinhardt, J. M. & Lin, S. Electrocatalysis as an Enabling Technology for Organic Synthesis. Chem. Soc. Rev. 50, 7941–8002 (2021).
Cheng, X., Lei, A., Mei, T.-S., Xu, H.-C., Xu, K. & Zeng, C. Recent Applications of Homogeneous Catalysis in Electrochemical Organic Synthesis. CCS Chem. 4, 1120–1152 (2022).
Zhang, W., Lu, L., Zhang, W., Wang, Y., Ware, S., Mondragon, J., Rein, J., Strotman, N., Lehnherr, D., See, K. & Lin, S. Electrochemically driven cross-electrophile coupling of alkyl halides. Nature 604, 292–297 (2022).
Zhang, B., Gao, Y., Hioki, Y., Oderinde, M. S., Qiao, J. X., Rodriguez, K. X., Zhang, H.-J., Kawamata, Y. & Baran, P. S. Ni-electrocatalytic Csp³–Csp³ doubly decarboxylative coupling. Nature 606, 313–318 (2022).
Chen, M., Wu, Z.-J., Song, J. & Xu, H.-C. Electrocatalytic Allylic C−H Alkylation Enabled by a Dual-Function Cobalt Catalyst. Angew. Chem. Int. Ed. 61, e202115954 (2022).
Li, P., Kou, G., Feng, T., Wang, M. & Qiu, Y. Electrochemical NiH-Catalyzed C(sp³)−C(sp³) Coupling of Alkyl Halides and Alkyl Alkenes. Angew. Chem. Int. Ed. 62, e202311941 (2023).
Tang, S., Liu, Y. & Lei, A. Electrochemical Oxidative Cross-coupling with Hydrogen Evolution: A Green and Sustainable Way for Bond Formation. Chem, 4, 27–45 (2018).
Röckl, J. L., Pollok, D., Franke, R. & Waldvogel, S. R. A Decade of Electrochemical Dehydrogenative C,C-Coupling of Aryls. Acc. Chem. Res. 53, 45–61 (2020).
Zhang, S., Li, L., Li, J., Shi, J., Xu, K., Gao, W., Zong, L., Li, G. & Findlater, M. Electrochemical Arylation of Aldehydes, Ketones, and Alcohols: from Cathodic Reduction to Convergent Paired Electrolysis. Angew. Chem. Int. Ed. 60, 7275-7282 (2021).
Zhang, S., Shi, J., Li, J., Li, M.-B., Li, G. & Findlater, M. Catalyst-Dependent Direct and Deoxygenative Coupling of Alcohols by Convergent Paired Electrolysis. CCS Chem. 4, 1938-1948 (2022).
Zhang, S. & Findlater, M. Progress in Convergent Paired Electrolysis. Chem. Eur. J. 28, e202201152 (2022).
Li, F., Liang, Y., Zhan, X., Zhang, S. & Li, M.-B. Electricity-driven redox-neutral C(sp³)–H amidation with N-alkoxyamide as an amidating reagent. Org. Chem. Front. 9, 5571-5577 (2022).
Li, C., Li, M., Li, J., Liao, J., Wu, W. & Jiang, H. Palladium-Catalyzed Aerobic Oxygenation of Allylarenes. J. Org. Chem. 82, 10912–10919 (2017).
Nelson, T. A. F. & Blakey, S. B. Intermolecular Allylic C−H Etherification of Internal Olefins. Angew. Chem. Int. Ed. 57, 14911–14915 (2018).
Xiong, P., Zhao, H.-B., Fan, X.-T., Jie, L.-H., Long, H., Xu, P., Liu, Z.-J., Wu, Z.-J., Cheng, J. & Xu, H.-C. Site-selective electrooxidation of methylarenes to aromatic acetals. Nat. Commun. 11, 2706 (2020).
Zhang, P.; Sheng, X.; Chen, X.; Fang, Z.; Jiang, J.; Wang, M.; Li, F.; Fan, L.; Ren, Y.; Zhang, B., Timmer, B. J. J., Ahlquist, M. S. G. & Sun, L. Paired Electrocatalytic Oxygenation and Hydrogenation of Organic Substrates with Water as the Oxygen and Hydrogen Source. Angew. Chem. Int. Ed. 58, 9155–9159 (2019).
Vantourout, J. C. From Bench to Plant: An Opportunity for Transition Metal Paired Electrocatalysis. Org. Process Res. Dev. 25, 2581–2586 (2021).
Yang, G., Jiao, Y., Yan, H., Xie, Y., Tian, C., Wu, A., Wang, Y. & Fu, H. Unraveling the mechanism for paired electrocatalysis of organics with water as a feedstock. Nat. Commun. 13, 3125 (2022).
Zong, L., Xiang, S., Sun, R. & Lu, Q. Selective C(sp³)–H arylation/alkylation of alkanes enabled by paired electrocatalysis. Nat. Commun. 14, 7992 (2023).
Wang, F. & Stahl, S. S. Electrochemical Oxidation of Organic Molecules at Lower Overpotential: Accessing Broader Functional Group Compatibility with Electron−Proton Transfer Mediators. Acc. Chem. Res. 53, 561–574 (2020).
Conway, B. E. & Tilak, B. V. Interfacial processes involving electrocatalytic evolution and oxidation of H₂, and the role of chemisorbed H. Electrochim. Acta 47, 3571–3594 (2002).
Marinescu, S. C., Winkler, J. R. & Gray, H. B. Molecular mechanisms of cobalt-catalyzed hydrogen evolution. Proc. Natl Acad. Sci. USA 109, 15127–15131 (2012).
McKone, J. R., Marinescu, S. C., Brunschwig, B. S., Winkler, J. R. & Gray, H. B. Earth-abundant hydrogen evolution electrocatalysts. Chem. Sci. 5,865–878 (2014).
Jiao, Y., Zheng, Y., Jaroniec, M. & Qiao, S. Z. Design of electrocatalysts for oxygen- and hydrogen-involving energy conversion reactions. Angew. Chem. Int. Ed. 54, 52-65 (2014).
Queyriaux, N., Jane, R. T., Massin, J., Artero, V. & Chavarot-Kerlidou, M. Recent developments in hydrogen evolving molecular cobalt (II)–polypyridyl catalysts. Coordin. Chem. Rev. 304, 3–19 (2015).
Zhao, G., Rui, K., Dou, S. X. & Sun, W. Heterostructures for Electrochemical Hydrogen Evolution Reaction: A Review. Adv. Funct. Mater. 28, 1803291 (2018).
Gnaim, S., Bauer, A., Zhang, H.-J., Chen, L., Gannett, C., Malapit, C. A., Hill, D. E., Vogt, D., Tang, T., Daley, R. A., Hao, W., Zeng, R., Quertenmont, M., Beck, W. D., Kandhari, E., Vantourout, J. C., Echeverria, P.-G., Abruna, H. D., Blackmond, D. G., Minteer, S. D., Reisman, S. E., Sigman, M. S. & Baran, P. S. Cobalt-electrocatalytic HAT for functionalization of unsaturated C–C bonds. Nature, 605, 687–695 (2022).
Wu, X., Gannett, C. N., Liu, J., Zeng, R., Novaes, L. F. T., Wang, H., Abruña, H. D. & Lin, S. Intercepting Hydrogen Evolution with Hydrogen-Atom Transfer: Electron-Initiated Hydrofunctionalization of Alkenes. J. Am. Chem. Soc. 144, 17783−17791 (2022).
Zhang, S., Liang, Y., Liu, K., Zhan, X., Fan, W.; Li, M.-B. & Findlater, M. Electrochemically Generated Carbanions Enable Isomerizing Allylation and Allenylation of Aldehydes with Alkenes and Alkynes. J. Am. Chem. Soc. 145, 14143–14154 (2023).
Zhang, S. & Findlater, M. Electrochemically Driven Hydrogen Atom Transfer Catalysis: A Tool for C(sp3)/Si–H Functionalization and Hydrofunctionalization of Alkenes. ACS Catal. 13, 8731–8751 (2023).
Song, L., Fu, N., Ernst, B. G., Lee, W. H., Frederick, M. O., DiStasio Jr, R. A. & Lin, S. Dual electrocatalysis enables enantioselective hydrocyanation of conjugated alkenes. Nat. Chem. 12, 747-754 (2020).
Yang, F., Nie, Y.-C., Liu, H.-Y., Zhang, L., Mo, F. & Zhu, R. Electrocatalytic Oxidative Hydrofunctionalization Reactions of Alkenes via Co(II/III/IV) Cycle. ACS Catal. 12, 2132−2137 (2022).
Deposition number 2313154 (for cat 1) contain the supplementary crystallographic data for this paper. These data are provided free of charge by Cambridge Crystallographic Data Centre.
Francke, R. & Little, R. D. Redox catalysis in organic electrosynthesis: basic principles and recent developments. Chem. Soc. Rev. 43, 2492–2521 (2014).
Badalyan, A. & Stahl, S. S. Cooperative electrocatalytic alcohol oxidation with electron-proton-transfer mediators. Nature, 535, 406-410 (2016).
Simmons, E. M. & Hartwig, J. F. On the Interpretation of Deuterium Kinetic Isotope Effects in C–H Bond Functionalizations by Transition-Metal Complexes. Angew. Chem. Int. Ed. 51, 3066– 3072 (2012).

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