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 visible-light-induced[3+2] annulation of arylcyclopropylamines and 1,2-diarylethanediones was report. A series of α-amino tetrahydrofuran derivatives were synthesized in moderate to good isolated yields under mild reaction conditions. This method would provide an efficient and convenient approach to α-amino tetrahydrofurans which are potentially important buiding blocks in bioactive compounds.

Trifluoromethylation using Togni reagents usually releases one equivalent of iodobenzoats as wasteful byproducts. A visible-light-mediated, atom-and step-economical hydrotrifluoromethylation of aromatic alkynes and remote benzoyl-oxylation of α-C(sp³)-H bond of ether with Togni reagent as a bifunctional reagent by means of hydrogen atom transfer strategy was disclosed. The combination of two organic transformations into one reaction not only brings 100% atom economy but also addresses the challenge of stereoselective hydrotrifluoromethylation of aromatic alkynes. This unprecedented protocol offers an important access to a wide range of highly functionalized CF₃-containing alkenes with great potential for post-modification.

Tremendous advance has been achieved for the transition-metal free coupling reactions induced by light these years, providing important strategies for the construction of C-N/S/P bonds, which was used frequently in the preparation of pharmaceutical drugs, agricultural products or materials and so on. In this review, the recent advance for the photo-induced coupling reactions for the construction of C-N/S/P bonds under transition-metal free conditions is reviewed.

Polyethylene glycols (PEG) can dissolve a lot of organic compounds and metallic complexes. Moreover, they are thermally stable, nonvolatile, non-toxic, biodegradable, inexpensive and recyclable. Thus, PEG as green medium has been successfully employed in many organic reactions, such as carbon-carbon coupling reaction, carbon-hetero coupling reaction, multicomponent reaction, condensation reaction, addition reaction, substitution reaction, oxidation reaction, reductive reaction, and so on. The recent advances of PEG applied in orgainc synthesis are reviewed.

An effective visible-light mediated Ru-catalyzed protocol for accessing 6H-benzo[c]chromenes from benzyloxybenzenediazonium salt via a sequence of dediazoniation, intramolecular radical cyclization and aromaticzation has been developed. The protocol features mild conditions, simple operation and high efficiency, providing a new approach for synthesizing 6H-benzo[c]chromenes.

Water is a medium for reaction in living organisms, which is safe, cheap and easy to obtain, and visible light is a clean and renewable natural resource. Exploring the controllable free radical reaction under the illumination condition in water and developing a simple, green and efficient synthesis method not only conform to the current green chemistry theme, but also have an important scientific significance in theory and practical application. The classification and review of visible light catalysis in aqueous phase have been carried out in recent years, and the corresponding mechanisms are discussed.

The cross dehydrogenation coupling reaction realizes direct coupling of two different X-H bonds to form a new chemical bond, thus featuring excellent step and atom economy. The traditional cross dehydrogenation coupling reaction was usually catalyzed by transition metal, which had the problems of expensive catalyst and serious pollution. Visible light-induced electron transfer is also an effective way to realize direct functionalization of X-H bonds. Visible-light-induced cross dehydrogenation coupling reaction under transition metal-free conditions is widely concerned due to the advantages of cleanliness, safety as well as high step and atom economy. Classified by the type of bonding, the research progress of these reactions is reviewed, and their future outlook is also discussed.

Visible-light-promoted organic synthesis is an important research hotspot and frontier in organic chemistry in recent years. Particularly, as a novel organic photosensitizer, 2, 4, 5, 6-tetrakis(carbazol-9-yl)-1, 3-dicyanobenzene (4CzIPN) has showed excellent catalytic performance in visible-light-induced radical reactions. The recent progress on the transition-metal-free photosynthesis under visible-light catalyzed by 4CzIPN is reviewed, and the application of 4CzIPN for photocatalytic organic transformations from different precursors (including silicon reagent, carboxylic acid and its derivatives, sulfur-containing reagent and fluorine reagent) is included.

The α-diazocarbonyl compounds are easy to prepare and can be dediazonized to highly reactive carbene intermediates under thermolytic or photolytic conditions. Chemical bonds can be efficiently constructed by carbene mediated reactions, including the insertion reaction of carbene into N-H bonds which is an effective method for constructing C-N bonds. The α-diazocarbonyl compounds have received extensive application in organic synthesis and pharmaceutical synthesis. The research progress in the insertion reaction of α-diazocarbonyl compounds into N-H bonds under transition metal, organic small molecules, biomacromolecule or photolytic and thermolytic conditions is summarized, including the reaction mechanism and synthesis applications. Finally, the prospects of this reaction are also discussed.

An efficient protocol for facile access to trifluoromethylated tetrahydrofuran and tetrahydropyran has been developed under visible light irradiation conditions via radical 1,2-alkoxyl-trifluoromethylation of unactivated alkene. It features the use of readily commercially available and operatively simple trifluoromethanesulfonyl chloride as a trifluoro- methyl radical source, thus making the protocol potentially appealing for practical preparation.

The traditional methods for synthesizing Z-olefins generally require the use of high-energy reagents. These methods are usually controlled by kinetics. The reaction conditions are harsh and low atom economic. During the process of separation, Z-olefins are easy to convert to the thermodynamically more stable E-olefins. With the continuous development of organic photochemistry and photocatalysis technology, more and more synthetic challenges have been solved by photocatalysis. Herein, various types of visible light-promoted photocatalytic isomerization of olefins are reviewed.

The synthesis of carbohydrates through photoredox catalysis has achieved a great process in the past decade. This review highlights the latest advances in this research area, including the photo-induced O-glycosylation and C-glycosylation, and the functional group modification and thiol-ene coupling reactions of carbohydrates.

A series of water-soluble sulfonated porphyrins have been synthesized and characterized by ¹H NMR, IR, UV-Vis, fluorescence and MS. The fluorescence quantum yield and lifetime of the series of porphyrins have been obtained. These porphyrins have been used as photocatalysts for the oxidation of 2,3-dihydroxynaphthalene. The main product has been proved to be 1,2-benzenedicarboxylic acid with the highest conversion rate of 91%. The effects of electron caused by different substituent groups and steric structure on sulfonated porphyrins photocatalytic activities have been investigated. It has been proved that substituent groups have electronic effects on the photocatalytic activities. The chosen of oxygen resource, the kinetics of the oxidation and the photocatalytic mechanism of sulfonated porphyrins have been investigated.

1,5-Bromotrichloromethylation of α-cyclopropylstyrenes via a radical chain pathway was achieved with Ir[dF(CF₃)ppy]₂(dtbbpy)PF₆ as a photoinitiator under visible-light irradiation to give trisubstituted styrenes with Z/E ratio of 30:70. When the reaction mixture was further irradiated, the Z/E ratio could be reversed and increased to 99:1, probably via an energy-transfer pathway involving the Ir photocatalyst. This visible-light-induced catalytic isomerization protocol could also be applied to trisubstituted styrenes to obtain products with Z/E ratios up to 99:1.

Imines are a class of active intermediates and have good antibacterial activity, therefore, they have received the extensive concern of scientists. Since the preparation method of imines by oxidative coupling of amines has the advantages of high atom economy and environmental friendliness, it has become a research hotspot. The recent progress in oxidative coupling of amines to imines is summarized from two aspects:catalyst and catalytic mechanism in this article. We introduced all kinds of catalytic systems in detail such as noble metal, non-noble metal, photocatalysis, biomimetic catalysis, poly aniline, graphite oxide, and azobisisobutyronitrile (AIBN). The catalytic performance, advantages and drawbacks and applicability of which are highlighted. And the catalytic mechanisms of the main catalytic systems are also discussed. It should be pointed out that these catalytic systems for oxidative coupling of amines to imines showed varying degrees of success as well as limitations like high cost of catalyst, harsh reaction condition, use of oxidant, alkaline additives and/or toxic organic solvents. Finally, based on the existential problems for oxidative coupling of amines to imines, the research directions in this field are predicted.

Aromatic boronic acids and esters are essential intermediates and have been widely used in biology, medicine and material science. In this paper, the resent progress on their synthesis is summarized, especially Pd-catalyzed borylation of aryl chlorides with steric hindrance substrates, other metal (Ni, Cu, Fe, Zn, Rh, Co)-catalyzed borylation, metal-free borylation, and photoinduced borylation.

Hydrogen production by artificial photosynthetic water splitting is an efficient approach to convert solar ennergy into chemical bonds. Oxygenation of an organic substrate based on light-driven water oxidation is innovative way to mimic the oxygen evolving center (OEC) in Photosystem Ⅱ. The metal catalyst will accomplish H₂O activation to generate high valent metal-oxo intermediate, which can transfer the oxygen atom to an organic substrate, during which the H atoms in H₂O molecule could be released. This review is a perspective of the recent advances in oxygenation of organic substrates with water as oxygen source. In the meanwhile, research prospect on photocatalytic hydrogen production coupled with the photocatalytic oxygenation of an organic substrate for a new water splitting system has been proposed.

A simple and practical visible-light-induced protocol has been developed for the construction of 3-arylquinoxa-lin-2(1H)-ones via Eosin Y-catalyzed direct C-H 3-arylation of quinoxalin-2(H)-ones with aryl diazonium salts at room temperature in air. The present reaction provides a cost-effective and operationally straightforward approach to the target products in moderate to good yields, and does not require any metal reagents, bases, acids, and strong oxidants.

Recently, the photo-induced radical reactions have emerged as a hot research topic in the field of organic synthetic chemistry. Among these, the radical acylation reaction via photocatalyst is one of the most effecient strategy to prepare ketones under mild conditions. The recent progress on the photo-induced reactions of acyl radical, various acyl radical sources and its application in the organic synthesis is summaried.

Oxime organic dyes, acting as photoredox catalysts, are widely used in visible-light-induced organic synthesis due to their advantages of low cost, good water solubility, high reactivity and so on. The type of organic dyes-catalyzed organic reactions is continuously expanding, and there is a tendency that organic dyes are gradually replacing some of transition metal catalysts. Classified by the type of reactions, the research progress of several common organic dyes in visible-light-induced organic synthesis in recent years is reviewed, and their future outlook is also discussed.

A practical strategy has been described for the preparation of trifluoroethyl-coumarin derivatives using a visible-light-promoted trifluoroethylation reaction of propiolate with trifluoroethyl iodide. These reactions could be carried out at room temperature in good chemical yields with good functional group tolerance.

The functional switch of a C—H activation directing group to a pharmacophore is introduced and analyzed, and the value of the pharmacophore and the application of C—H activation are exemplified. It is concluded that many pharmacophores, such as N-containing heteroaromatic, nitrile, carboxylic acid, amide and sulfonamide groups, are ideal directing groups for C—H activation enabling the subsequent stages of drug synthesis, and showing that there is a correlation between a directing group and a pharmacophore. The late-stage functionalization will greatly simplify and effectively improve the possibility of discovering new drugs and potentially shortening the overall synthesis. The latest breakthroughs of C—H activation and application in the drug discovery process are reviewed as case studies, providing several industrial examples of using a pharmacophore as directing group for drug synthesis. It is believed that this development will promote a more rapid and green drug synthesis.

The scientists have been working on developing more efficient and green ways to synthesize organophosphorus compounds as they have broad utilities such as reagents for chemical reactions, photovoltaic materials, flame retardants, biologically active molecules and so on. The difunctionalization reactions between P-center radicals and unsaturated compounds provide powerful methods for the synthesis of organophosphorus compounds in least and concise steps. This review will summarize the recent development in this area on the basis of different types of P-centered radical initiators.

Transition metal-catalyzed C-H activation is one of the most important areas in organic synthesis. Directed C-H activation can obviate the prefunctionalization of substrate, therefore providing a highly efficient and concise strategy for C-C formation. The cross-coupling of transition metal-activated C-H bond with organic electrophilic reagents has been proven effective for construction of various C-C bonds. Meanwhile, the oxidative coupling between the corresponding intermediates with organometallic reagents has become the focus for chemists due to their high reactivity, and notable achievements have been made in recent years. Here the oxidative couplings of C-H bond and organometallic reagents have been discussed and summarized according to the hybridization of substrate and organometallic reagents.