A transition-metal-free and chemical oxidant-free method was developed for the uniform synthesis of 4-arylselanylanilines and 4-alkylselanylanilines through electrolytic selenylation of N-unprotected anilines with diorganyl diselenides under mild conditions in an undivided cell. The present approach had good functional group compatibility, which made it to be a green and practical method to synthesize 4-(organylselanyl)anilines.

A series of ester compounds were synthesized by direct oxidative coupling of aldehydes with alcohols. The electrosynthesis reaction can be carried out at room temperature without inert gas protection, external oxidants, N-heterocyclic carbene (NHC) catalyst and alkali (such as DBU (1,5-dizzabicyclo[5.4.0]undecen-5-ene)), etc. The oxidative esterification reaction processes in a simple and easily available undivided electrochemical cell and constant current mode. This protocol features mild reaction conditions, broad substrate scope, cheap and easily available starting materials, and simple operation, providing a new strategy for the green synthesis of ester compounds.

Electrochemical organic synthesis is considered as an environmentally benign method because it employs traceless electrons as redox agents, thereby avoiding the need for chemical oxidants. The electrochemical decarboxylative acylation of isocyanides and relay hydration reaction for the synthesis of α-ketoamides was developed. This reaction can be carried out under mild conditions in the absence of a chemical oxidant and a transition-metal catalyst.

Indole, as one of the most important nitrogen-containing heterocyclic compound, is found widely in various natural products and synthetic drugs. 3-Iodoindoles play an important role as intermediate in the selective functionalization of indoles. 3-iodoindoles could be conveniently synthesized by electrochemical annulations of o-alkynylanilines with readily available iodide salt. This sustainable electrolysis strategy provides an efficient access to a series of 3-iodoindoles in good to excellent yields under external oxidant-free, base-free conditions and features broad functional group tolerance.

Quinoxalinone and its derivatives are a class of important nitrogen heterocyclic compounds, which widely exist in natural products, drugs and functional materials. Therefore, the C—H functionalization of quinoxalinone has attracted extensive attention of chemical workers. In recent years, electrochemical synthesis directly uses electron as a “clean reagent” to participate in redox reaction without additional redox reagent, which has the characteristics of mild reaction conditions and good atom economy. This method meets the requirements of green chemistry and sustainable development. With the in-depth study on the mechanism of electrochemical synthesis and the standardization of reaction equipment, this method has become a powerful tool for functionalization of quinoxalineones. The recent advances in the electrochemical C(3)—H functionalization of quinoxaline-2(1H)-one are summarized. The reaction transformation conditions and mechanisms are systematically discussed, and the challenges and future directions of this field are included.

Selenium-containing heterocycles are a kind of important organic molecules, which are widely used in medicine, agrochemicals, organic materials and other fields. Therefore, the introduction of selenium atom into organic molecules is of great significance in synthetic chemistry. Visible light and electrochemical technology is one of the green and sustainable synthesis methods, which has opened up broad application prospects in the fields of bifunctionalization and cyclization of unsaturated bonds and direct functionalization of C—H bonds. In recent years, the development of novel selenium cyclization reaction using photoelectric technology to drive unsaturated bonds and direct selenization reaction of C—H bonds has attracted much attention. Therefore, this paper describes the electrochemical-driven and visible-light-induced synthesis reactions of selenium-containing heterocycles, and discusses the applicable scope and mechanism of some reactions.

Following the renaissances of organic electrochemistry and photochemistry, photoelectrochemical approach was arising as one of hot research areas by combination advantages of photocatalysis and electrocatalysis. The photoeletrocatalysis was widely applied in redox reactions, coupling reactions and beyond. The development of photoelectrochemical transformations during past five years is summarized and the related reactions are classified according to mechanism and catalyst. The current progresses and future outlooks of such method are also discussed.

α-Aryl(alkyl)selenyl ketones have been important intermediates in organic transformation. Here, a new route to α-aryl (alkyl) selenoacetones via the electrochemical oxidated iodide promoted α-H aryl(alkyl)selenation of acetone by using stable and easy available diaryl(alkyl)diselenides as selenide reagent is reported. Comparing to the previous methods, this strategy has the advantages of mild reaction conditions, high atom economy and wide functional groups tolerance, providing an efficient and green route to α-aryl (alkyl) selenoacetones.

Quinoxalin-2(1H)-ones are a kind of important nitrogen-containing heterocyclic compounds, which have strong biological activity and chemical properties, and play an important role in synthesis chemistry, functional materials, drugs and so on. In recent years, the construction of 3-functionalized quinoxalin-2(1H)-one by C—H functionalization has attracted the attention of many scholars and made important progress. Among them, green chemistry oriented photocatalysis and electrochemical synthesis are becoming powerful tools for C—H functionalization of quinoxaline-2(1H)-one. In view of the great influence of photochemistry in synthetic chemistry, the research status of C—H functionalization of quinoxaline- 2(1H)-one in visible light catalysis and electrochemical synthesis is summarized, hoping to promote the further development of green synthesis strategy in the functionalization of nitrogen-containing heterocycles.

Due to the pivotal role of tailor-made amino acids in modern medicinal chemistry research and drug design, the interest in the development of synthetic methodology for preparation of these compounds is at an all-time high. Currently, electrochemical approaches for synthesis of amino acids are being actively pursued to take the advantage of sustainability and green chemistry facets offered by the electrochemistry. This work presents the first specially focused, comprehensive treatment of the literature data related to synthesis of amino acids via electrochemical means. Aspects of practicality, benefits and current shortcoming of this approach are critically discussed.

Metal-free electrochemical oxidation cyanation and phosphonylation reactions had been developed, in which 2,2,6,6-tetramethylpiperidinyl-N-oxyl (TEMPO) reduced the electrode potential of substrate and avoided over oxidation of some electron rich aromatic amines under electrochemical conditions. This protocol had good functional group compatibility, which made it to be a practical and efficient method to synthesize α-aminonitriles and α-amino phosphonates under mild conditions. Preliminary study indicated that the formation of the product was through the Shono oxidation of imine species.

β-Amido sulfone motif reprents a particularly useful scaffold for the biologically active molecules. The hydrogenation ofβ-amidovinyl sulfon is an alternative method to synthesizeβ-amido sulfone. Herein, one electrochemical method to synthesizeβ-amido sulfone using sodium sulfites and tertiary amines as substrates is presented. OnlyE-configurations ofβ-amidovinyl sulfonyl were synthesized under metal catalyst- and oxidant-free condition. Cyclic voltammetry (CV) and control experiments indicate that this electrosynthesis reaction goes through a radical process which the sulfonyl radical adds to enamine to form the carbon radical.

Minisci reaction, an important method for the construction of new carbon-carbon bonds, refers to one kind of the radical substitution reactions between a nucleophilic carbon radical and an electron-deficient nitrogen-containing aromatic heterocycle. Besides, organic electrosynthesis is experiencing a renaissance as a green synthesis technology and means. This review focuses on the recent advances in Minisci reactions under electrochemical conditions.

C—N bonds are widely existed in drugs, natural products, and functional materials. Thus, the construction of C—N bonds is one of the most important research areas in academia and industry. Recently, the renaissance in organic electrochemistry has promoted the electrochemical C—N bond formations to be a special branch of organic synthesis. The most recent advances in the electrochemical C—N bond formations since 2015 are summarized. The reaction mechanisms of these transformations are discussed, and the challenges and future directions of this important filed are included. We hope that this review can give references to the researchers, graduate students and other related people.

1,2,4-Triazoles, standing for a class of five-membered nitrogenous heterocyclic compounds, show anti-inflam- matory, anti-fungal and other biological activities. They also served as important intermediates in organic synthesis. Thus, the pursuit of general and efficient synthesis of 1,2,4-triazoles that controls the introduction of substituents in a highly regioselective fashion has been of continued interest to synthetic organic chemists. In this paper an electrochemical dehydrogenative [3+2] annulation used for the synthesis of 1,2,4-triazoles from cheap and readily available amines and hydrazones was developed. Their structures were confirmed by ¹H NMR, ¹³C NMR and HRMS analyses. Advantageously, this method proceeds in a transition-metal-, acid-, base- and external oxidant-free fashion to provide a variety of functionalized 1,2,4-triazoles. The reaction constitutes a new transformation from hydrazones and amines to 1,2,4-triazoles, providing a unifying, simple and environmentally friendly approach to the currently available methods.

Quinazolinone is one of the most important nitrogen-containing heterocyclic compound, which is widely found in numerous natural products and synthetic drugs. Quinazolinone derivatives were synthesized by one-pot co-oxidation of benzyl alcohol with CuCl₂ and electric current in aqueous phase. The reaction provides an efficient protocol to a series of quinazolinones derivatives in good to high yields. This synthesis process features convenient operation and environmental friendliness, which make it a promising method for the preparation of quinazolinone derivatives insteading of expensive and toxic oxidants with electric current.

A series of sulfenamide compounds are synthesized by electrooxidation of thiophenols and amines. The electrosynthesis reaction does not require metal catalysts and oxidizing reagents, and uses simple devices such as single- chamber electrolyzers and constant current electrolysis. This method featured broad substrate scope, ready availability of starting materials, operational simplicity and environmental friendly, which provides a new strategy for the simple and convenient synthesis of various sulfenamide derivatives.

Imidazo[1,2-a]pyridines are a special nitrogen-containing compounds, which play an important role in the fields of pesticides biomedicine, optical and electrical materials. In recent years, the synthesis of functional imidazo[1,2-a]pyridines has become a hot topic for organic scientists and pharmaceutical chemists, and great progress has been made. Among them, the synthesis of functionalized imidazo[1,2-a]pyridines via visible-light catalysis and electrochemistry based on green chemistry has become the powerful tool for the synthesis of these compounds. Based on the types of canbon-hetero bonds of imidazo- [1,2-a]pyridines, the research on the construction of imidazo[1,2-a]pyridines C-3 canbon-hetero bonds by visible-light catalysis and electrochemical synthesis in recent 5 years is summarized.

Nitrogenous heterocyclic compounds are widely found in medicinal molecules, natural products and functional materials. Therefore, it has great significance to develop simple and efficient methods for the construction of these compounds. Recently, remarkable progress has been made in haloids mediated electrochemical synthesis of nitrogen heterocycles. Due to the relatively mild reaction condition and environmental protection, it provides a novel approach to construct nitrogen heterocycles. In this review, the recent developments in this area are summarized.

Fluorine chemistry has been widely used in all walks of life, and the combination of fluorine chemistry and organic chemistry is blooming everywhere. Since the introduction of fluorine atoms or fluorine groups into drugs is of great significance, it is essential to seek an effective fluoroalkylation pathway. With the development of electrochemistry, people combine electrochemistry and fluoroalkylation reaction skillfully. In turn, a safer, more economical, environmentally friendly and efficient fluoroalkylation pathway is obtained. The fluoroalkylation reaction pathway under the guidance of electrochemistry has not only reformed the reaction method, but also has advantages in terms of substrate universality. Fluoroalkylation of unsaturated aliphatic compounds their derivatives and aromatic compounds under electrochemical catalysis has been reported. According to the nature of the substrate and its reaction mechanism, the progress of electrocatalytic fluoroalkylation methods is summarized.

Olefin is an important synthetic synthon, and its concise and efficient transformation has been a research hotspot in the field of organic synthesis. In recent years, the C—S bond formation based on the olefin skeleton has received particular attention from scientists. Alkenes can react with common organic sulfur-containing reagents, including thiol, disulfide, sulfoxide, sulfonyl hydrazide, sulfonyl chloride, sodium sulfinate and other kinds of organosulfur reagents to build C—S bonds at the α-position or β-position of olefin to synthesize sulfide, sulfoxide or sulfone. Thus, according to the different classification of the used organosulfur reagents, the recent research progresses in C—S bond formation reaction of olefins with organic sulfur reagents under photocatalyst-free conditions and non-electrochemical method is summarized. In the future, among the researches on the C—S bond formation reactions of olefins with inexpensive organosulfur reagents, asymmetrical synthesis and various difunctionalizations are still promising directions.

The recent developments in asymmetric organotransition metal-catalyzed electrochemistry (AOMCE) are summarized. AOMCE processes can be divided into oxidative and reductive variants. In terms of oxidations, asymmetric functionalization of olefins, oxidative kinetic resolution of secondary alcohols or aldehydes, and asymmetric C—H functionalization reactions have been developed. Reductive processes discussed include asymmetric electrochemical carboxylation with carbon dioxide, asymmetric electrochemical decarboxylation, and asymmetric reductive coupling reactions. The combination of chiral ligands, transition-metal catalysts, and electrochemistry provides a novel angle by which to address the longstanding fundamental challenge of stereoinduction in traditional electrochemical organic synthesis.

An electrochemical selenylation/cyclization of N-allylthioamides has been developed for the synthesis of selenium-containing 2-thiazolines. This protocol provides an efficient approach to produce 2-thiazolines with broad substrate scope under mild reaction conditions. Preliminary mechanistic study indicates that selenium radical may be involved. The reaction is easy operated under catalyst- and oxidant-free conditions.

1,3,4-Oxadiazoles, standing for a class of five-membered heterocyclic compounds with multiple heteroatoms, show anti-inflammatory, anti-convulsant, anti-inositol and other biological activities. They also served as important intermediates in organic synthesis. Thus, the development of general and straightforward methods for their synthesis is of great significance. In this paper one-step synthesis of non-symmetric 2,5-disubstituted 1,3,4-oxadiazole derivatives with good yield was completed under electrocatalytic conditions by using cheap and readily available aldehydes and hydrazides as starting materials. Their structures were confirmed by IR, ¹H NMR, ¹³C NMR and HRMS analyses. The reaction features mild conditions, high atom-economy and wide substrate scope, providing a green and sustainable synthetic protocol for constructing 1,3,4-oxadiazole skeleton.

Thiocyanate, as a versatile synthon, which has important application value in many fields such as pharmaceutical, pesticide and materials. The photocatalytic and electrocatalytic thiocyanation reactions have been widely concerned in organic chemistry due to the advantages of green, efficiency and safety. In this review, the cross-coupling/thiocyanation reactions based on the photocatalytic and electrocatalytic are described, which is expected to be helpful in exploring the green synthesis of thiocyanates compounds.