Electrochemical Cross-coupling Research Articles

Electrochemical Cross-Coupling between N-(4-Hydroxyphenyl)-sulfonamides and 2-Naphthols: Synthesis of 2,2'-Bis(arenol)s.

We herein present an electrochemical method for the dehydrogenative cross-coupling of N-(4-hydroxyphenyl)-sulfonamides and 2-naphthols. This transformation provides a direct and scalable approach to a wide range of C1-symmetric 2,2'-bis(arenol)s with moderate to high yields under mild conditions. Preliminary attempts with the asymmetric variant of this reaction were also performed with ≤55% ee for the synthesis of 2,2'-bis(arenol)s. Control experiments were conducted to propose a plausible mechanism for the reaction.

Nickel-Electrocatalytic Decarboxylative Arylation to Access Quaternary Centers.

There is a pressing need, particularly in the field of drug discovery, for general methods that will enable direct coupling of tertiary alkyl fragments to (hetero)aryl halides. Herein a uniquely powerful and simple set of conditions for achieving this transformation with unparalleled generality and chemoselectivity is disclosed. This new protocol is placed in context with other recently reported methods, applied to simplify the routes of known bioactive building blocks molecules, and scaled up in both batch and flow. The role of pyridine additive as well as the mechanism of this reaction are interrogated through Cyclic Voltammetry studies, titration experiments, control reactions with Ni(0) and Ni(II)-complexes, and ligand optimization data. Those studies indicate that the formation of a BINAPNi(0) is minimized and the formation of an active pyridine-stabilized Ni(I) species is sustained during the reaction. Our preliminary mechanistic studies ruled out the involvement of Ni(0) species in this electrochemical cross-coupling, which is mediated by Ni(I) species via a Ni(I)-Ni(II)-Ni(III)-Ni(I) catalytic cycle.

Metal Cations from Sacrificial Anodes Act as a Lewis Acid Co-Catalyst in Electrochemical Cross-Coupling of Aryl Bromides and Aziridines

An efficient method for the reductive cross-electrophile coupling of aziridines with aryl halides using nickel electrocatalysis is reported. This reaction provides valuable phenethylamines at room temperature in good yields. The reaction was successfully applied to the electro-reductive cross-coupling of less reactive, unsubstituted N-tosylaziridine. Additionally, we were even able to couple challenging alkyl bromides with aryl aziridines. Control experiments and voltammetric studies confirm that the mechanism is distinct from conventional and photochemical couplings. Furthermore, the role of both Ni(II) organometallic complexes and electrodes was examined, providing insight into the reaction mechanism and the beneficial role of the sacrificial anode in electrochemical cross-couplings.

Electrochemical Cross-Coupling Reactions between Arylboronic Esters and Aryllithiums Using NaBr as a Halogen Mediator

AbstractAn electrochemical cross-coupling reaction between arylboronic esters and aryllithiums was developed. The presence of Br– in the electrolyte was found to be essential for the reaction. NaBr was chosen as the electrolyte for its inexpensiveness and abundance, and also acted as a halogen mediator. The reaction proceeded under mild conditions to afford biaryls.

Electrochemical Suzuki–Miyaura cross-coupling using peptide bolaamphiphile hydrogel-supported Pd NPs as heterogeneous electrocatalyst

Electrochemical cross-coupling has arisen as one of the promising greener approaches for the construction of C–C bonds.

Theoretical investigation of mechanism on nickel-catalyzed electrochemical cross-coupling of aryl bromides and arylamines

The electrochemical cross-coupling of aryl bromides and arylamines catalyzed by nickel/bipyridine complexes was explored using density functional theory (DFT) calculations. The steric and electronic effects on the catalyst were further analyzed.

Electrochemical Cross-Coupling of Arenes under Flow Conditions

Key words azolation - arenes - electrochemistry - cross-coupling

Nickel-Catalyzed Paired Electrochemical Cross-Coupling of Aryl Halides with Nucleophiles

AbstractElectrochemistry has recently gained increased attention as a versatile strategy for achieving challenging transformations at the forefront of synthetic organic chemistry. However, most electrochemical transformations only employ one electrode (anodic oxidation or cathodic reduction) to afford the desired products, while the chemistry that occurs at the counter electrode yields stoichiometric waste. In contrast, paired electrochemical reactions can synchronously utilize the anodic and cathodic reactions to deliver the desired product, thus improving the atom economy and energy efficiency of the electrolytic process. This review gives an overview of recent advances in nickel-catalyzed paired electrochemical cross-coupling reactions of aryl/alkenyl halides with different nucleophiles.1 Introduction2 Nickel-Catalyzed Cross-Coupling Reactions2.1 C–C Bond Formation2.2 C–N Bond Formation2.3 C–S/O Bond Formation2.4 C–P Bond Formation3 Conclusion

Electrochemical Deoxygenative Thiolation of Preactivated Alcohols and Ketones.

This work describes an electrochemically promoted nickel-catalyzed deoxygenative thiolation of alcohols and ketones under mild conditions. Excellent substrate tolerance and good chemical yields can be achieved by graphene/nickel foam electrodes in an undivided cell. Further study to gain mechanistic insight into this electrochemical cross-coupling has been carried out.

Nickel-Catalyzed Electrochemical Cross-Coupling of Alcohols and Aryl Halides

Nickel-Catalyzed Electrochemical Cross-Coupling of Alcohols and Aryl Halides

Copper or Silver-Mediated Oxidative C(sp2)–H/N–H Cross-Coupling of Phthalimide and Heterocyclic Arenes: Access to N-Arylphthalimides

Copper or silver-catalyzed direct C(sp2)–H/N–H electrochemical cross-coupling of phthalimide and heterocyclic arenes (2-phenylpyridine, benzo[h]quinoline, benzoxazole, and benzothiazole, etc.) for ...

Electrochemical cross-coupling of biogenic di-acids for sustainable fuel production

Tailored electrochemical cross-coupling enables a flexible modular access to bio-fuels starting from biomass derived mono- and di-acids and renewable energy.

Unsymmetrical Biaryl Compounds: Metal- and Reagent-Free Electrochemical Couplings Are on the Advance.

It's electrifying! Electrochemical cross-coupling of aryl compounds provides a one-step approach to unsymmetrical biaryl compounds. A boron-doped diamond electrode is used as the anode to oxidise the phenolic hydroxy group to a phenoxy radical, with 1,1,1,3,3,3-hexafluoroisopropylalcohol (HFIP) and tetraalkylammonium methylsulfate used as the solvent and electrolyte. Since no reagents are required, no waste is formed from this source.

Unexpected high robustness of electrochemical cross-coupling for a broad range of current density.

Electro-organic synthesis is a powerful technique for the sustainable preparation of compounds. However, many electrosynthetic reactions require complex equipment, are limited to a very narrow current density range, or have very long reaction times; some also involve nonselective transformations and bad scalability. The robust and selective synthesis of nonsymmetric biphenols and partially protected derivatives is established by anodic C-C cross-coupling. The setup is simple, involving constant current conditions and undivided cells. Its key is a unique electrolyte system based on fluorous alcohols and mixtures, particularly 1,1,1,3,3,3-hexafluoroisopropanol. This allows variations of the current density of more than two orders of magnitude without decreasing selectivity or product yield. This exceptional effect is unknown for electro-organic synthesis of products that have similar oxidation potentials as the starting materials. It potentially paves the way for industrial electrolyzers with variable current consumption, which could enable the flexible use of energy surplus in the electricity supply.

Synthesis of C3-Fluorinated Oxindoles by Electrochemical Cross-Coupling

Synthesis of C3-Fluorinated Oxindoles by Electrochemical Cross-Coupling

Cover Picture: Source of Selectivity in Oxidative Cross‐Coupling of Aryls by Solvent Effect of 1,1,1,3,3,3‐Hexafluoropropan‐2‐ol (Chem. Eur. J. 35/2015)

Precisely adjusted solvates. influence the oxidation potential of substrates for the electrochemical cross-coupling of arenes. The solvent mixture based on 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) and MeOH gives rise to a decoupling of nucleophilicity from the oxidation potential. In their Full Paper on page 12321 ff., S. R. Waldvogel and co-authors rationalize the outstanding selectivity of the anodic cross-coupling. This solvent effect explains also the selectivity previously found by HFIP mixtures. Precisely adjusted solvates. influence the oxidation potential of substrates for the electrochemical cross-coupling of arenes. The solvent mixture based on 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) and MeOH gives rise to a decoupling of nucleophilicity from the oxidation potential. In their Full Paper on page 12321 ff., S. R. Waldvogel and co-authors rationalize the outstanding selectivity of the anodic cross-coupling. This solvent effect explains also the selectivity previously found by HFIP mixtures. Pincer catalysts Amino Acids for Live-Cell Labeling Bimetallic Tadpoles

Impact of multicomponent ionic transport on pH fronts propagation in saturated porous media

AbstractWe investigate the propagation of pH fronts during multicomponent ionic transport in saturated porous media under flow‐through conditions. By performing laboratory bench‐scale experiments combined with numerical modeling, we show the important influence of Coulombic effects on proton transport in the presence of ionic admixtures. The experiments were performed in a quasi two‐dimensional flow‐through setup under steady‐state flow and transport conditions. Dilute solutions of hydrochloric acid with MgCl2 (1:2 strong electrolyte) were used as tracer solutions to experimentally test the effect of electrochemical cross coupling on the migration of diffusive/dispersive pH fronts. We focus on two experimental scenarios, with different composition of tracer solutions, causing remarkably different effects on the propagation of the acidic fronts with relative differences in the penetration depth of pH fronts of 36% between the two scenarios and of 25% and 15% for each scenario with respect to the transport of ions at liberated state (i.e., without considering the charge effects). Also differences in the dilution of the distinct ions plumes up to 28% and 45% in experiment 1 and 2, respectively, were measured at the outflow of the flow‐through system. The dilution of the pH plumes also changed considerably (26% relative difference) in the two flow‐through experiments only due to the different composition of the pore water solution and to the electrostatic coupling of the ions in the flow‐through setups. Numerical transport simulations were performed to interpret the laboratory experiments. The simulations were based on a multicomponent ionic formulation accurately capturing the Coulombic interactions between the transported ions in the flow‐through system. The results of purely forward simulations show a very good agreement with the high‐resolution measurements performed at the outlet of the flow‐through setup and confirms the importance of charge effects on pH transport in porous media.

Multicomponent ionic dispersion during transport of electrolytes in heterogeneous porous media: Experiments and model-based interpretation

This study investigates the effects of Coulombic interactions during transport of electrolytes in heterogeneous porous media under steady-state flow and transport conditions. We performed flow-through experiments in a quasi two-dimensional setup using dilute solutions of strong 1:1 and 1:2 electrolytes to study the influence of electrochemical cross-coupling on mass transfer of charged species in saturated porous media. The experiments were carried out under advection-dominated conditions (seepage velocity: 1 and 1.5m/day) in two well-defined heterogeneous domains where flow diverging around a low-permeability inclusion and flow focusing in high-permeability zones occurred. To quantitatively interpret the outcomes of our laboratory experiments in the spatially variable flow fields we developed a two-dimensional numerical model based on a multicomponent formulation and on charge conservation. The results of the multicomponent transport simulations were compared with the high-resolution concentration measurements of the ionic species at the outlet of the flow-through domain. The excellent agreement between the measured concentrations and the results of purely forward numerical simulations demonstrates the capability of the proposed two-dimensional multicomponent approach to describe transport of charged species and to accurately capture the Coulombic interactions between the ions, which are clearly observed in the flow-through experiments. Furthermore, the model allowed us to directly quantify and visualize the ionic interactions by mapping the Coulombic cross-coupling between the dispersive fluxes of the charged species in the heterogeneous domains.

An Electrochemical Nickel-Catalyzed Arylation of 3-Amino-6-Chloropyridazines

3-Amino-6-aryl- and 3-amino-6-heteroarylpyridazines have been obtained in generally good yield using a nickel-catalyzed electrochemical cross-coupling between 3-amino-6-chloropyridazines and aryl or heteroaryl halides at room temperature. Comparative experiments involving classical palladium-catalyzed reactions, such as Suzuki, Stille, or Negishi cross-couplings, reveal that the electrochemical method can constitute a reliable alternative tool for biaryl formation. A possible reaction mechanism is proposed on the basis of electrochemical analyses.

Some mechanistic aspects of a nickel-catalyzed electrochemical cross-coupling between aryl halides and substituted chloropyridazines

Abstract The nickel-2,2′-bipyridine catalyzed electrochemical cross-coupling reaction between an aryl halide and a chloropyridazine was investigated by an electrochemical study. The electrochemical behavior of the divalent nickel complex is affected by the presence of pyridazine rings which act as co-ligands of nickel. Cyclic voltammetry indicates that the cross-coupling reaction involves first a rapid oxidative addition of the chloropyridazine on the electrogenerated zerovalent nickel complex. The coupling product is then obtained by reaction with the aryl halide.