Organic Chemistry: Current Research
Open Access

Study on Application of Electrochemical Methods to the Synthesis of Organic Molecules

Laura Bertolasi^{* *}Correspondence: Laura Bertolasi, Department of Organic Chemistry, Medical University of Gdansk, Gdansk, Poland, Email:

Author info »

Description

The application of electrochemical techniques to the synthesis of organic molecules has undergone a revival during the last few decades. In terms of the ecological footprint and the replacement of chemical redox reagents with electricity is an unavoidable advance towards green chemical processes. The advancements incorporate the consolidation of electrochemistry with conventional chemical ideas, for example, organocatalysis and flow electrochemistry, as well as new systems for controlling the selectivity of electrochemical changes, like, the "cation-pool" technique, the redox-tag approach, and bio-electrochemistry. All electrochemical methods depend on basic electron moves from the electrode to the substrate or vice versa. In electroorganic syntheses, about three distinct situations for the electron to move from the electrode to the substrate are achievable. For this situation, the electroconversion happens at the electrode surface and selectivity can be accomplished by changing the appropriate cathode potential [1]. Generally, the utilization of novel organic synthesis generally depends on the utilization of inert electrodes, since reactivity is not determined by a surface layer.

Direct electrolysis enables molecules to go through electron transfer directly at the terminal or electrode surface. However, with indirect electrosynthesis, a redox mediator which is more oxidized or reduced than the substrate goes about as the electron-transfer shuttle from the heterogeneous cathode surface to the homogeneously dissolved substrates. The indirect approach brings about improved reaction viability and better chemoselectivity by keeping away from undesirable side reactions. The homogeneous redox process eliminates kinetic inhibition of the heterogeneous electron transfer and the underlying change of the mediator offers direct selectivity control. In this context, the advantageous impacts of redox mediators were recently exemplified for the difficult selective anodic oxidation of actuated C-H bonds, which ended up being valuable for the change of natural products [2]. The electrochemical direct allylic oxidation can engage the electrogenerated alkyl radical with the fragmentation of the cyclobutane ring to enable the immediate oxidation of α-pinene. A crucial step was made by Masui, utilizing Nhydroxyphthalimide (NHPI) as an electron transporter to work with allylic C-H oxidations.

In contrast to indirect electrolysis, double electrocatalysis enables two particular catalytic changes that go beyond electron transfer, including not being restricted to, group transfer reactions, hydrogen atom transfer, or two individual reactant ideas, like mediated electrochemistry and photoredox catalysis. It was demonstrated to be an efficient strategy to improve catalytic performance, chemoselectivity, and general catalytic efficacy [3]. The proposed reactant situation comprises the initial formation of the catalytically competent [CoIII]-H species, framed from the anodically oxidized cobalt(III) salen complex and a hydrosilane. Ensuing Hydrogen-Atom Transfer (HAT) between the formal [CoIII]-H intermediate and olefin 8 furnishes the new C-H bond, together with a carbon-centered radical. The radical species currently enters a second electrocatalytic cycle that is liable for the asymmetric cyanide transfer. Here, formed radical species are proposed to go through single-electron oxidative addition to a [CuII]-CN complex, producing a copper(III) adduct.

Finally, the reductive end from the chiral complex conveys the enantio-enhanced nitrile and a reduced copper(I) complex, which is effectively reoxidized through anodic oxidation. The merger of two distinct electrocatalytic radical reactions, i.e., cobalt-catalyzed Hydrogen-Atom Transfer (HAT) and coppercatalyzed radical cyanation, was the way to practice the asymmetric hydrocyanation of alkenes. In addition, the electrocatalysis convention featured further developed yields, chemoselectivities, and enantioselectivities compared with transformations using chemical oxidants, as was exemplified by the failure of topical oxidants, for example, Nfluorobenzenesulfonimide (NFSI), tert-butyl hydroperoxide (TBHP), Cu(OAc)₂, and PhI(OAc)₂.

The synergism of electrochemistry and photochemistry has started significant current interest with various electrophotocatalytic reactions being disclosed to achieve extreme redox potentials. The quest for a well-designed electrophotocatalyst for a united co-activity with electrocatalysis as well as inherent scalability stays an extensive obstacle. Electrochemical change of small molecules has indeed thrived in recent years; in any case, there have been restricted efforts to further use them in organic synthesis [4,5]. Introducing CO₂ as a C1 synthon gives a greener alternative for organic synthesis related to electrochemical methods. The global view for compound synthesis has been connecting far renewable methodologies and chemical sources, and we expect more advances to be made on this path toward an effective change of CO₂ and N₂ to valuable synthetic materials.

Recent improvements in asymmetric electrochemical changes have prompted synthetic applications in organic synthesis with good functional group tolerance and high enantioselectivity. The quick development of electrosynthesis strongly relies upon detailed insights into electroorganic reactions. Subsequently, this method is expected to continue to unravel the mechanism of electrosynthesis by characterization of short-lived intermediates and give further experiences into fundamental Single Electron Transfer (SET) processes.

References

1. Schneider N, Stiefl N, Landrum GA. What’s what: The (nearly) definitive guide to reaction role assignment. J Chem Inf Model. 2016;56: 2336-2346.

   [CrossRef] [Google Scholar] [PubMed]

2. Rahman SA, Cuesta SM, Furnham N, Holliday GL, Thornton JM. EC-BLAST: A tool to automatically search and compare enzyme reactions. Nat Meth. 2014;11: 171-174.

   [CrossRef] [Google Scholar] [PubMed]

3. Akutsu T. Efficient extraction of mapping rules of atoms from enzymatic reaction data. J Comp Biol. 2004;11: 449-462.

   [CrossRef] [Google Scholar] [PubMed]

4. Latendresse M, Malerich JP, Travers M, Karp PD. Accurate atom-mapping computation for biochemical reactions. J Chem Inf Model. 2012;52: 2970-2982.

   [CrossRef] [Google Scholar] [PubMed]

5. Chen WL, Chen DZ, Taylor KT. Automatic reaction mapping and reaction center detection. Wiley Inter Rev Comput Mol Sci. 2013;3: 560-593.

   [CrossRef] [Google Scholar]