Electrochemical oxidation of some dihydroxybenzene derivatives in the presence of indole

Renewable Electricity Enables Green Routes to Fine Chemicals and Pharmaceuticals

Syntheses of chemicals using renewable electricity and when generating high atom economies are considered green and sustainable processes. In the present state of affairs, electrochemical manufacturing of fine chemicals and pharmaceuticals is not as common place as it could be and therefore, merits more attention. There is also a need to turn attention toward the electrochemical synthesis of valuable chemicals from recyclable greenhouse gases that can accelerate the process of circular economy. CO₂ emissions are the major contributor to human-induced global warming. CO₂ conversion into chemicals is a valuable application of its utilisation and will contribute to circular economy while maintaining environmental sustainability. Herein, we present an overview of electro-carboxylation, including mechanistic aspects, which forms carboxylic acids using molecular carbon dioxide. We also discuss atom economies of electrochemical fluorination, methoxylation and amide formation reactions.

Recent advances in electrochemically driven radical fluorination and fluoroalkylation

Electrochemical fluorination (ECF) refers to the introduction of fluorine-containing moieties into organic molecules under electrochemical conditions.

Biomimetic Oxidative Coupling Cyclization Enabling Rapid Construction of Isochromanoindolenines

Herein, we report a biomimetic oxidative coupling cyclization strategy for the highly efficient functionalization of tetrahydrocarbolines (THCs). This process enables rapid access to complex isochromanoindolenine scaffolds in moderate to excellent yields. The reaction proceeds smoothly and rapidly (complete within minutes) in an open flask. This operationally simple protocol is scalable and compatible with a wide range of functional groups. Late-stage functionalization of a pharmacologically relevant molecule is also demonstrated.

Electrochemical strategies for C-H functionalization and C-N bond formation

Conventional methods for carrying out carbon-hydrogen functionalization and carbon-nitrogen bond formation are typically conducted at elevated temperatures, and rely on expensive catalysts as well as the use of stoichiometric, and perhaps toxic, oxidants. In this regard, electrochemical synthesis has recently been recognized as a sustainable and scalable strategy for the construction of challenging carbon-carbon and carbon-heteroatom bonds. Here, electrosynthesis has proven to be an environmentally benign, highly effective and versatile platform for achieving a wide range of nonclassical bond disconnections via generation of radical intermediates under mild reaction conditions. This review provides an overview on the use of anodic electrochemical methods for expediting the development of carbon-hydrogen functionalization and carbon-nitrogen bond formation strategies. Emphasis is placed on methodology development and mechanistic insight and aims to provide inspiration for future synthetic applications in the field of electrosynthesis.

A green strategy for the synthesis of sulfone derivatives of p-methylaminophenol: Kinetic evaluation and antibacterial susceptibility

This is one of the few examples in which the diverse products have been synthesized just by changing the applied potential. The synthesis of sulfonyl derivatives of p-methylaminophenol were carried out by reaction of the electrogenerated p-methylquinoneimine with sulfinic acids. Various types of mono (MSP), bis (BSP) and tris (TSP) sulfonyl p-methyl aminophenols were obtained by changing the electrode potential, in one pot under green conditions. The mono sulfonyl-p-(methylamino)phenol derivatives (MSP) were assessed for their in vitro antibacterial activity against the gram positive (Staphylococcus aureus) and gram negative (Escherichia coli) strains. It was found that the tested compounds were more active against Staphylococcus aureus than Escherichia coli. We also found that the antimicrobial activity of MSP derivatives to vary in the order MSP₄ (R = CH₃) > MSP₁ (R = p-tolyl) ≈ MSP₂ (R = phenyl) > MSP₃ (R = p-ClC₆H₄). Moreover, the observed homogeneous rate constants (k_obs) of the reaction of p-methyl quinoneimine with sulfinic acids were estimated in various pH values, based on the EC and ECEC mechanisms, by comparing the simulated cyclic voltammograms with the experimental ones.

New insights into the electrochemical behavior of acid orange 7: Convergent paired electrochemical synthesis of new aminonaphthol derivatives

Electrochemical behavior of acid orange 7 has been exhaustively studied in aqueous solutions with different pH values, using cyclic voltammetry and constant current coulometry. This study has provided new insights into the mechanistic details, pH dependence and intermediate structure of both electrochemical oxidation and reduction of acid orange 7. Surprisingly, the results indicate that a same redox couple (1-iminonaphthalen-2(1H)-one/1-aminonaphthalen-2-ol) is formed from both oxidation and reduction of acid orange 7. Also, an additional purpose of this work is electrochemical synthesis of three new derivatives of 1-amino-4-(phenylsulfonyl)naphthalen-2-ol (3a-3c) under constant current electrolysis via electrochemical oxidation (and reduction) of acid orange 7 in the presence of arylsulfinic acids as nucleophiles. The results indicate that the electrogenerated 1-iminonaphthalen-2(1 H)-one participates in Michael addition reaction with arylsulfinic acids to form the 1-amino-3-(phenylsulfonyl)naphthalen-2-ol derivatives. The synthesis was carried out in an undivided cell equipped with carbon rods as an anode and cathode.

Electrochemical generation of a Michael acceptor: a green method for the synthesis of 4-amino-3-(phenylsulfonyl)diphenylamine derivatives

A green electrochemical method for the synthesis of 4-amino-3-(phenylsulfonyl) diphenylamine derivatives via the reaction of N-phenylquinonediimine with arylsulfinic acids is reported.

A green approach for the synthesis of bis (substituted sulfabenzamide) para-benzoquinone based on the reaction of sulfabenzamide with electrochemically generated para-benzoquinone and its antibacterial evaluation

The electrochemical synthesis of a new bis (substituted)p-benzoquinone was carried outviathe electrooxidation of hydroquinone in the presence of sulfabenzamide

Electrochemically induced cross-dehydrogenative coupling (CDC) reaction. An efficient electrochemical method for the synthesis of dicoumarols

Electrochemical synthesis of dicoumarols was carried out by the electrochemical oxidation of N,N,N′,N′-tetramethyl-1,4-phenylenediamine in the presence of 4-hydroxycoumarin derivatives.

Kinetic and mechanistic study of drug–drug interaction between acetaminophen and β-lactam antibiotics

This article focuses on the drug–drug interaction between acetaminophen (also known as paracetamol) and β-lactam antibiotics (amoxicillin, ampicillin and penicillin) studied by means of cyclic voltammetry and controlled potential coulometry. The results indicate a drug–drug interaction between N-acetyl- p-benzoquinone-imine (NAPQI) derived from the anodic oxidation of acetaminophen and β-lactam antibiotics. Also the cyclic voltammetric data were analysed by digital simulation to measure the observed homogeneous rate constants ( kobs) of the reaction of NAPQI with β-lactam antibiotics. The calculated kobs for the reaction between NAPQI and β-lactam antibiotics was found to vary in the order kobsamoxicillin = kobsampicillin> kobspenicillinat biological pH.

Electrochemical Behavior of Biologically Important Indole Derivatives

Voltammetric techniques are most suitable to investigate the redox properties of a new drug. Use of electrochemistry is an important approach in drug discovery and research as well as quality control, drug stability, and determination of physiological activity. The indole nucleus is an essential element of a number of natural and synthetic products with significant biological activity. Indole derivatives are the well-known electroactive compounds that are readily oxidized at carbon-based electrodes, and thus analytical procedures, such as electrochemical detection and voltammetry, have been developed for the determination of biologically important indoles. This paper explains some of the relevant and recent achievements in the electrochemistry processes and parameters mainly related to biologically important indole derivatives in view of drug discovery and analysis.

Electrochemical oxidation of catechols in the presence of phenyl-Meldrum's acid. Synthesis and kinetic evaluation

Electrochemical oxidation of catechols in the presence of phenyl-Meldrum's acid as a nucleophile in aqueous solution has been studied in detail by means of cyclic voltammetry and controlled potential coulometry. The results indicate that the o-benzoquinone derived from catechols participates in Michael addition reaction with phenyl-Meldrum's acid to form corresponding products. We derived some new "highly oxygenated compounds with catechol ring" with good yields based on electrochemical oxidation in the controlled potential condition in aqueous solutions, without toxic reagents and solvents at carbon electrode in an undivided cell, using an environmentally friendly method. Furthermore, the observed homogeneous rate constants (k(obs)) of the chemical reaction between o-benzoquinone and phenyl-Meldrum's acid were estimated by comparing the experimental cyclic voltammetric curves with the digitally simulated ones.