A visible-light-induced oxidative cyclization of N-propargylanilines with arylsulfonylhydrazides was developed using tert-butyl hydroperoxide as oxidant. This transformation offers a straightforward route to 3-sulfonated quinoline derivatives with good functional group tolerance, good to excellent yields and high regio-selectivity.

4-Alkyl Hasntzch esters are good alkyl radical storage. The preparation of multisubstituted α,β-unsaturated carboxylic acid esters under photocatalytic redox conditions by 4-alkyl Hantzsch esters and Baylis-Hillman adducts was investigated. The reaction conditions are mild and no additional additives are required. The coupling products were obtained in moderate to good yields.

A novel synthetic route for the total syntheses of 1-benzoyl-3,4-dihydroisoquinoline alkaloids was developed. Nelumstemine was synthesized for the first time via 6 steps in 50% overall yield starting from 3,4-dimethoxybenzaldehyde, and longifolonine was also synthesized for the first time via 9 steps in 35% overall yield starting from vanillin. The key step of these total syntheses is photo-oxidation of 1-benzyl-3,4-dihydroisoquinolines to 1-benzoyl-3,4-dihydroisoquinolines by air under visible-light irradiation at room temperature. The unique mild photo-oxidation of 1-benzyl-3,4-dihydro-isoquinolines has been studied in detail.

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.

Benzofulvenes were widely found in natural products and bioactive molecules, and also served as important building blocks in material science and transition-metal chemistry. Great efforts have been devoted to the efficient synthesis of these interesting molecules, and rapid advancement has been made in the past two decades. According to the types of the initiation of the reaction, these methods can roughly be classified into five categories:thermal or photochemical cyclization of enyne-al-lenes or enediynes, transition metal-catalyzed sequential cyclization reaction, electrophilic or nucleophilic attack initiated cyclization, radical initiated cyclization and acid promoted cyclization. This review describes the important synthetic methods of benzofulvenes according to their reaction types.

Alkyl carboxylic acids are among the most ubiquitous organic molecules found in nature. The reactions using abundant carboxylic acid and its derivatives as starting materials deserve widespread attention over the world. They are often easy to generate alkyl radical by photoredox catalysis under mild conditions for building various chemical bonds in organic chemistry. Based on the reaction modes, decarboxylation of alkylcarboxylic acids and their derivatives, the recent progress in decarboxylation of alkylcarboxylic acids and their derivatives under visible light is reviewed.

Over the last decades, the transition metal-catalyzed cross-coupling reactions have become powerful organic synthetic methods for forming carbon-carbon and carbon-heteroatom bonds. Very recently, the introduction of visible light into transition metal catalysis opened a new avenue for achieving novel, highly enabling cross-coupling reactions that otherwise were elusive. This type of reaction has received extensive attention due to its simple, mild conditions and no need of photocatalyst. Based on the classification of transition metals, the research progress of transition metal-catalyzed cross-coupling reactions directly promoted by visible light is reviewed.

The photocatalytic redox reactions have been widely concerned in organic chemistry due to their green, efficiency and safety. In this review, the cross-coupling/aromatization reactions are described based on photocatalytic organic hydrogen-evolution, which can be used to build organic carbon-carbon and carbon-heteroatom bonds by using a photocatalyst/catalyst dual catalytic system. Hydrogen is the only by-product in these reactions. The system and catalytic mechanisms of organic photocatalytic redox reaction are highlighted.

A photocatalyzed method for the synthesis of δ-ketonitriles from the reaction of diaryl allyl alcohols with bromoacetonitrile is developed. The result of control experiments indicates that the reaction might proceed via a free radical mechanism and bromoacetonitrile was the source of cyanomethyl radical.

Herein, the visible-light-induced α-C(sp³)—H amination reactions of tertiary amines were reported. By using readily available 1,3-dioxoisoindolin-2-yl benzoate as precursor of N-radical and blue LEDs as green and sustainable energy source, the α-C(sp³)—H bonds of various N,N-dimethylaniline derivatives were aminated directly. Based on radical trapping experiment and documented literature, a mechanism involving radicals coupling was proposed. This method featured in mild reaction conditions and good functional group tolerance, which provides a simple and practical protocol to the modification of tertiary amines.

A novel visible-light-introduced reaction for the construction of benzimidazole derivatives via radical cyclization of o-phenylenediamines with benzonitrile derivatives in water has been developed. The reaction has been achieved in high yield under mild conditions by using Eosin Y as photocatalyst, which is cheap, easy to handle and environmentally friendly. A variety of benzimidazoles were obtained in up to 91% yields. It might provide a promising protocol for the synthesis of benzimidazole derivatives.

A novel visible-light-introduced reaction for the construction of phenols via hydroxylation of aryl halides has been developed. The reaction has been achieved in high yield under mild conditions by using iodine as photocatalyst, which is cheap, easy to handle and environmentally friendly. A variety of phenols were obtained in up to 92% yields. Moreover, aryl chlorides were also successfully employed as substrates, affording the target phenols in good isolated yields. It might provide promising protocol for the synthesis of phenol derivatives. Its application was performed by the synthesis of 5-acetyl-4-hy-droxy-2-methoxybenzyl diisopropylcarbamodithioate, which displayed significant anti-proliferation effect.

A photocatalytic Z to E isomerization of monofluorostilbenes in the presence of visible light (blue LEDs) has been developed. The transformation, which proceeds through a selective energy transfer pathway with Ir(Ⅲ) complex, offers facile access to thermodynamically less stable E-monofluoroalkenes with synthetically useful efficiency (up to 96% yield, up to 91:9 E:Z). Mild reaction conditions, good functional groups tolerance, and broad substrate scope were observed. Furthermore, the synthetic utility of this method is demonstrated by the rapid synthesis of monofluorinated cis-DMU-212 analogue E-30.

1,2-Diiodoalkenes can be used as precursors for synthesis of functional molecules such as heterocyclic drugs and organic conjugated materials due to their derivability of functional groups. Herein, alkynes can be converted into 1,2-trans-diiodioalkenes efficiently and conveniently by using inexpensive and stable sodium iodide as iodine source and air as oxidant under the visible-light (blue light) with normal temperature and atmospheric pressure. The corresponding reactions were operated under mild conditions with inexpensive and easily accessible reagents, which obviate the need of transition-metal-catalysts or oxidizing reagents. Meanwhile, this method is compatible with a wide range of substrates, including terminal and internal alkynes even the peptide and carbohydrates containing a variety of heteroatoms and active hydrogen.

Fluoroalkylated alkenes are of significant importance in life sciences and functional materials. The fluoroalkylation of alkynes offers an efficient method for the synthesis of functionalized fluoroalkylated alkenes. However, the current methods are often limited to 1,2-difunctionalization, while the remote fluoroalkylative difunctionalization of alkynes has been rarely developed. Herein, a novel visible-light-induced remote halo-difluoroalkylation of thioalkynes is realized with difluoroalkyl halides as the radical source, forming distally halogenated (Z)-fluoroalkylated alkenes in moderate to high yields with excellent regio-, stereo-, and site-selectivity. The notable features of this reaction include the mild reaction conditions, broad substrate scope, concurrent formation of three new chemical bonds, and a thermodynamically less stable (Z)-alkene, thus enabling it a highly attractive method for organic synthesis. It represents a new advance on the direct C-H bond halogenation. Preliminary mechanistic studies indicate a cascade radical process involving the heteroatom-induced β-fluoroalkylation of C-C triple bonds, intramolecular 1,5-hydrogen atom transfer (1,5-HAT), single electron transfer (SET) oxidation and halide addition.

Organoboron compounds are valuable synthetic intermediates and widely used in the synthesis of medicine, pesticide and organic optoelectronic materials due to their extensive resouce and highly transformable ability. Among various organoboron compounds, the synthesis and transformation of alkylboron compounds have attracted much attention. As a sustainable and green energy, visible light shows an important effect in organic systhesis. Tetracoordinated alkylboron compounds could occur single electron transfer (SET) process to generate alkyl radical for further transformations. Herein, the recent advances in the photoinduced transformation of alkyl boron compounds are summarized.

In recent years, decatungstate [W₁₀O₃₂]^4- as a catalyst has attracted much attention in the field of photocatalytic organic synthesis. With the catalysis of decatungstate, the C—H bond of substrate can be converted into the corresponding radical via a hydrogen atom transfer (HAT) progress under light irradiation. In this review, we summarized the recent advances of the application of decatungstate as a photocatalyst for the C—H functionalization to construct C—C, C—N, C—F bonds.

A mild method for the conversion of alkyl iodides to alcohols was developed. The transformation was promoted by tris(trimethylsilyl)silane/O₂ and accelerated by photoredox catalysis under visible light irradiation conditions. Various alkyl iodides, including primary, secondary and tertiary iodides, can be smoothly converted to the corresponding alcohols in 38%~99% yields.

Methylation of arenes is one of the versatile approaches to achieve structural modification in organic and medicinal chemistry. Installation of a methyl group onto an aromatic ring can lead to significant improvenent of the physical properties and biological activity of this molecule, thusly the effect oftentimes is called the“magic methyl effect”. During the past few years, visible-light-induced photocatalysis has emerged as a powerful tool for the development of efficient transformations in organic synthesis. Compared to traditional radical mediated reactions, the use of visible light as energy input is more environmentally benign. Recently, a series of aryl methylation reactions enabled by visible light photoredox catalysis have been reported and applied in the synthesis of pharmaceutically-interested products. In this review, the recent progress of visible-light-induced aryl methylation reactions is briefly summaried, with discussions of different reaction pathways.

Palladium-catalyzed organic transformations is an important branch of organometallic chemistry. Because it can efficiently construct carbon-carbon bonds and carbon-heteroatom bonds, palladium catalysis has been widely used in synthetic chemistry, material science and pharmaceutical industry. However, some of these reactions suffer from harsh reaction conditions, including high temperature and strong base. On the other hand, the visible-light photoredox catalysis employs the visible light as the energy source to generate highly reactive intermediates and realize many novel transformations, which are rare under the normal thermal reaction conditions, under mild reaction conditions. However, there are also limitations in reaction types and substrate scope in this field. In order to solve such problems in these two fields, organic chemists have merged the visible-light photoredox catalysis and palladium catalysis, realizing a series of novel organic transformations through the electron transfer or energy transfer between photosensitizer and organic palladium complex under mild conditions with high efficiency and selectivity, which has broad substrate scope and great application potential. In these transformations, visible-light photoredox catalysis and palladium catalysis both play their respective roles and cooperate well. The application of visible light photoredox and palladium dual catalysis in organic synthesis is summarized and the future research directions in this field are analyzed, which might help the further development of this field.

A visible-light driven asymmetric Giese radical addition catalyzed by a bifunctional chiral-at-metal rhodium complex has been developed. para-Aminobenzyl radicals generated from para-aminophenylacetic acids could undergo a 1,4-addition in a highly enantioselective approach to α,β-unsaturated 2-acyl imidazoles, and a variety of corresponding adducts were obtained in moderate to high yields with excellent enantioselectivities. This reaction features high enantioselectivity, mild reaction conditions and an operationally simple procedure. A plausible reaction mechanism is proposed based on our research and literature precedents on dual functional chiral-at-metal catalysis.

The advent of visible light photoredox catalysis has transformed the way of single-electron transfer (SET) processes and accessing radical species. As a result, the chemistry of nitrogen-centered radicals has witnessed a remarkable gain in interest. Specifically, under visible light photoredox catalysis, iminyl radicals can be generated from oxime derivatives, such as O-acyl oximes, O-aryl oximes and α-imino-oxy acids. Meanwhile, the reactivity of iminyl radcials is investigated systematically. Iminyl radicals can undergo four major classes of reactions, namely addition to arenes, intramolecular hydrogen atom transfer and subsequent reactions, addition to alkenes, Norrish type-I fragmentation (cleavage of α-carbon-carbon bonds) and subsequent reactions. In this review, the most significant progresses in the use of oximes and their derivatives as iminyl precursors are discussed and their engagement in photoredox-mediated transformations is outlined.

The recent applications of porous organic polymers (POPs) as heterogeneous catalysts for visible light-induced organic transformations are summarized. POPs are constructed from conjugated organic monomers, having the features of convenient synthesis and characterization, high stability for quick recovery and reuse, structural diversity as well as high modifiability. POPs possess rigid conjugated frameworks, relatively large surface areas, tunable porosity and typically insoluble in water or organic solvents, and thus ideal platforms for the development of heterogeneous catalysts. Through incorporating conjugated sensitizer units into the backbones or attaching the sensitizers to the backbone linkers, POPs can be developed as efficient heterogeneous photocatalysts for visible light-induced organic transformations. Due to their high stability and insolubility, POP catalysts can be easily recovered through filtration or centrifugation and recycled. POP-based photocatalysis combines visible light utility and catalyst recycling and thus represents a green and sustainable technique.

Phenanthrene derivatives play an important role in pharmaceutical chemistry and material science. Due to its advantages of green, mild reaction conditions and great application potential, visible light catalysis has become a powerful tool in organic synthesis. In this paper, under the catalysis of photocatalyst Ir[dF(CF₃)ppy]₂(dtbbpy)PF₆, a series of 10-phenanthrenol derivatives were synthesized from 2-arylbenzoyl acetate derivatives in moderate to good yields through intramolecular cycloaromatization. In addition, the plausible reaction mechanism was also proposed.

An eco-friendly visible light-induced approach for the synthesis of vinyl sulfones from the reaction of nitroolefins with sulfinic acid under photocatalyst free conditions was developed. Simple operation, mild reaction conditions, broad substrate scope and good yields of the desired products made this transformation have an excellent prospect. The anti-microbial activity test showed that some of the desired products had moderate inhibitory rate against V. mali and C. glecosporioides.

Photoredox catalysis has become a universal tool to catalyze a wide variety of chemical reactions with high selectivity under mild conditions. However, traditional photocatalysis relies heavily on photocatalysts with the problems such as high price and environmental pollution. Because iodine and iodide have the advantages of cheap, non-toxic and unique photoreactivity, their application in photochemical synthesis has attracted more and more attention in recent years. The research progress of photo-redox catalysis reactions mediated by iodine and iodide in recent years is summarized, and their future outlook is also discussed.

A novel visible-light-introduced reaction for the construction of quinazolinone derivatives via radical cyclization of 2-aminobenzamides with benzyl alochols under water phase has been developed. The reaction has been achieved in high yield under mild conditions by using I₂ as photocatalyst, which is cheap, available and easy to handle. A variety of quinazolinones were obtained in yields up to 92%. It might provide a promising protocol for the synthesis of quinazolinone derivatives. Its application was performed by the synthesis of N-(2-fluoro-5-methylphenyl)-6-(2,2,2-trifluoroethoxy)pteridin-4-amine, which displayed significant inhibitory activity.

Because of its low cost and environmental friendliness, visible light catalysis has been widely used in organic synthesis in recent years. Among them, α-aminoalkyl radical plays an important role because of its high activity and accessibility. The development and application of this active radical in visible light catalysis are mainly summarized and its outlook in the future is given.