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.

An efficient and facile method has been developed for the synthesis of quaternary carbon propargylamines via a one-pot tandem reaction of amines, alkynes, and alkynes under neat condition. Both aliphatic and aromatic terminal alkynes are well compatible with the established reaction, with respect to aliphatic alkynes, AgOTf was used as catalyst for the Markovnikov amine-alkyne-alkyne coupling process. When aromatic alkynes were used as substrates, the reaction was promoted by CuBr₂/Zn (OTf)₂ co-catalytic system. This tandem reaction exhibits excellent atom efficiency and provides an attractive approach to a diverse range of quaternary carbon propargylamines.

Deep eutectic solvent based on L-proline and oxalic acid has been demonstrated for the first time as an efficient catalyst for synthesis of 4,7-dihydro-1H-pyrazolo[3,4-b] pyridine-5-carbonitrile derivatives via one-pot three-component reaction of aldehyde, 3-oxopropanenitrile and 1H-pyrazol-5-amine. The key features of this approach include the broad substrate scope, operational simplicity, recyclable catalyst and possibility to scale up giving multigram quantities.

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.

Aromaticity is one of the most fundamental concept in organic chemistry. Aromatic compounds generally present special thermodynamic stability. Research on aromaticity can help us to understand the stability essence of aromatic compounds, and thus enables the further prediction and construction of species with stabilization or destablization. The endless richness of aromaticity researches usually originates the nature and criterion of aromaticity. The main emphasis of this review is on a discussion of historical discoveries, definitions and classification of aromaticity-related structural types, as well as various theoretically and experimentally criterions. Furthermore, this review contains the recent development of aromaticity illustrated by recent representative examples.

Porous organic polymer fluorescence materials have the characteristics of high porosity and outstanding fluorescence properties. The function of fluorescence sensing is given when the skeleton has binding sites with specific analytes, such as nitroaromatic explosives (NAEs), metal ions, anions, gases, organic solvents, etc. In this paper, according to the different types of porous organic polymer materials (POPs), namely the amorphous porous organic polymer materials, crystal porous metal organic framework materials (MOFs) containing coordination bond, and crystal covalent organic framework materials (COFs), the new progress of the POPs fluorescence materials in recent years is reviewed. Especially, the design and synthesis based on functional organic molecules, and their fluorescence sensing applications, are introduced in details. In the future, continuing to design new types of fluorescent COFs from the molecular level is a development direction of highly efficient and recyclable fluorescence chemosensors for detecting NAEs, metal ions, anions, etc.

Ferrocenes bearing planar chirality have been demonstrated to be highly efficient ligands or catalysts in asymmetric catalysis. In view of their atom and step economies, direct asymmetric C—H bond functionalization is the most concise and powerful method for the construction of planar chiral ferrocenes compared with traditional approaches. This review summarizes recent progress on the development of novel methods to synthesize planar chiral compounds via transition- metal (Cu-, Pd-, Ir-, Rh-, Au-, Pt-) catalyzed asymmetric C—H bond functionalization. Preparation of a variety of new planar chiral ferrocene-based catalysts and ligands by utilizing these methods and their application in catalytic asymmetric reactions are also discussed.

The C (sp³)-H adjacent to heteroatoms can be readily functionalized to C-C, C-N, C-O bonds etc. via cascade[1, n]-hydride transfer/cyclization, which shows high potency to construct 5-membered, 6-membered and all carbon rings. This intriguing cascade process can be employed to synthesize common skeletons of significant natural products and pharmaceutical molecules. Chiral amines, Lewis acids and Brønsted acids have been successfully utilized to catalyze the asymmetric cascade reaction.

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.

Amines containing carbon-nitrogen (C-N) bonds are widely distributed in natural products, drug molecules and functional materials. C-N bonds are one of the most abundant and inert bonds in organic molecules. Selective cleavage of C-N bonds to construct carbon-carbon (C-C) and carbon-heteroatom (C-X) bonds represents a new synthetic method in organic synthesis. It is difficult for the direct cleavage of C-N bond. Ammonium salts are a series of stable compounds easily obtained from amines. The recent progress of transition-metal-catalyzed cross-coupling reactions via C-N bond cleavage using ammonium salts as starting materials is summerized.

C-H bonds are widely existed in almost all the organic compounds. Transition-metal-catalyzed C-H functionalizations usually have high reaction efficiency and high atom-economy. However, traditional strategies based on such transition-metal catalyzed C-H activations generally result in poor selectivities, because C-H bonds in one molecule facilely display similar reactivity. It is difficult to be utilized in preparation of natural products, pharmaceuticals and biomolecules. However, directing group can induce the metal to activate proximal C-H bonds via cyclometallated intermediates, improve the regioselectivity of the transformations. Therefore, it is extremely significant to deveplop auxiliary-induced C-H bonds activations. The research progress of directing group-induced C-H activation reactions and mechanisms for recent ten years are sumarized.

A mild, general and efficient method for the direct synthesis of diverse amides from commercially available carboxylic acids and isothiocyanates has been developed. The strategy does not require stoichiometric amounts of coupling reagents or metal catalysts, and is especially for sterically hindered and electron-deficient secondary amides, which are otherwise challenging to synthesize.

Carbon-hydrogen bonds are the most extensive and basic chemical bonds existed in organic compounds. Electrochemical functionalization and direct conversion of aromatic C—H bonds is a green, sustainable, and atomically economical transformation pathway, which avoids the pre-functionalization of reactants. The anodic electrooxidation of aromatics allows the formation of C—X (X=C, N, O, S) bonds and the preparation of fused aromatic rings without the use of oxidants. Certain C—H activation reactions with chemoselectivity and regioselectivity can also be achieved by the optimization of electrode materials, electrolytes, and solvents. Vourious reactions focusing on the electrochemical functionalizations of C—H bonds in aromatic compounds are mainly reviewed.

Six 2/6-aryl substituted azulene derivatives 1～6 were designed and synthesised. Compounds 1～3 and 4～6 are 2-and 6-substituted derivatives, respectively, where the arly substituents were pentafluorobenzene, benzene and α-thiophene. The UV-Vis spectra, fluorescence spectra, electrochemical properties and proton-responsive properties of 1～6 were studied. To investigate the molecular sturcture, absorption spectra and energy levels of compounds 1～6, density functional theory (DFT) calculations were carried out. In comparison with the UV-Vis spectra of azulene, the absorption of S₀→S₂ transition of 1～6 showed red-shift (Δλ=6～68 nm). Owing to the strong electron-donating ability of α-thiophene group, remarkable bathochromic shifts of 3 and 6 (Δλ=68 and 48 nm, respectively) were obseved. The fluorescence spectra revealed that 4 (?_F=0.082) has the highest fluorescence quantum yield of 1～6, while 1-H⁺ (?_F=0.359) has the highest fluorescence quantum yield of the protonated compounds 1-H⁺～6-H⁺, benefiting from the electron-withdrawing pentafluorophenyl group of 1 and 1-H⁺. Moreover, the electrochemical analysis and DFT calculations demonstated that the introduction of electron-withdrawing pentafluorophenyl unit in the 2/6-positon of azulene can significantly lower the energy levels of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). In comparison with the HOMO/LUMO energy levels of azulene, those of 1 and 4 shift downward with ΔE_HOMO/ΔE_LUMO of －0.23/－0.18 and －0.20/－0.15 eV, respectively. The investigations of physical/chemical properties of 2/6-aryl substituted azulene derivatives will provide valuable insights for developing azulene-based organic functional molecules.

Helicenes are a kind of π-conjugated helical compounds which are consisted of ortho-fused benzene or other aromatic rings. Compared to other kinds of chiral catalysts, studies on helicene-based catalysts with helical chirality showed late start and lagging development. However, since helicene molecules exhibit structural rigidity, thermal stability, easily functionalization, and excellent chiral environment for asymmetric catalysis by continuous elaborate curve in three-dimensional space, investigation on the synthesis of helicene-based chiral catalysts and their applications in asymmetric catalysis have attracted increasing interest in recent years. According to the different roles of the helicenes played in the asymmetric catalysis, the helicene-based catalysts can be classified into chiral inducers, helically chiral ligands and helical organocatalysts, and their applications in asymmetric catalysis will be focused on in this review, respectively.

Fluorescent imaging technology has received great attention owing to their advantageous features in high sensitivity, relatively simple operations and real-time living cells, tissue and in vivo imaging. Compared with one-photon confocal imaging, two-photon confocal imaging offers considerable advantages such as high resolution, deep-tissue depth, lower tissue auto-fluorescence and so on. As typical D-π-A two-photon dyes, 1,8-naphthalimide dyes have wide application in two-photon imaging for enzyme, reactive carbon species, reactive oxygen species, reactive nitrogen species, biothiols and ions due to their advantages such as high photostability, large Stokes/anti-Stokes shifts. According to the mechanisms of intramolecular charge transfer, photoinduced electron transfer and fluorescence resonance energy transfer, etc., the application in two-photon imaging of 1,8-naphthalimide dyes is summarized and emphasized.

The sulfoximine derivatives are widely known for their potent biological and medicinal activities. Recently, due to the transition-metal catalysis, great advancements have been achieved in the synthesis of sulfoximine derivatives. Utilizing free NH-sulfoximines as the starting materials, various the direct N-H functionalizations can be accomplished, such as alkynylation, alkenylation, alkylation, arylation, etc. In addition, the ortho arene C(sp²)-H activation can also be obtained through C-H activation reaction with the assistance of S=NH as intramolecular directing groups, thus giving varies (hetero)aromatic molecules. N-H and C-H functionalization reactions of sulfoximines were summarized, and the mechanisms of some novel model reactions are also briefly discussed.

Among the numerous bio-active species which are involved in the various chemical reactions in our body, reactive oxygen species (ROS) are a class of important biological species, which are oxidative. ROS can maintain the intracellular redox balance and are tightly related with the cell growth and death. Hence, the fluorescence detection of intracellular ROS has attracted wide attention. However, owining to the inherent features of ROS, such as the short lifetime and high reactivity, fluorescence analysis of ROS is always faced with some problems, like low selectivity and side reactions. Herein, the development of small molecular fluorescent probes for intracellular ROS over the past decade is summarized, and the design mechanisms and bio-applications of these probes are emphasized.

Stimuli-responsive supramolecular drug delivery systems (SDDSs) self-assembled by supra-amphiphiles have received tremendous attentions in cancer therapy due to various advantages of SDDSs, such as enhanced drug bioavailability, prolonged blood circulation and retention time, improved drug stability and so on. The construction of smart supramolecular drug delivery systems based on the different structural characteristics of macrocyclic compounds are reviewed and their recent applications in anti-cancer drug delivery are described. Advantages and drawbacks of the current supramolecular drug delivery systems are also discussed, along with the opportunities and challenges in future.

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.

Pyrrolidines and pyrrolines, as important building blocks, are widely applied in the fields of medicine, agriculture and materials. Many synthetic methods for the preparation of pyrrolidines and pyrrolines have been reported over the past few years. Recently, following the rapid development of organometallic chemistry, the metal-catalyzed functionalization of unsaturated hydrocarbons has gradually become the research focus of organic synthesis methodology, due to the high efficiency and diversity of functionalization. Therefore the constructions of pyrrolidines and pyrrolines using metal-catalyzed unsaturated hydrocarbon functionalization are important and very useful. The development of metal-catalyzed functionalizations of different types of unsaturated hydrocarbons for the synthesis of pyrrolidines and pyrrolines is summarized.

A novel CuI-catalyzed trifluoromethylation of non-terminal enamides was investigated. N-Arylvinyl-substituted benzamide reacted with Togni reagent in dichloroethylane to afford N-(3,3,3-trifluoro-2-arylprop-1-en-1-yl) substituted benzamide. The reaction proceeded at 90℃ in air atmosphere in the presence of base and ligands. Control experiment shows that the Togni reagent firstly released CF₃ radical in the presence of copper(I) salts and CF₃ radical selectively added to the carbon-carbon double bond of β-position of enamides.

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.

Sixteen novel myrtenal-derived 2-acyl-1,2,4-triazole-3-thione compounds were designed and synthesized in search of new bioactive compounds. Their structures were confirmed by FTIR, NMR, ESI-MS and elemental analysis. The in vitro antifungal and herbicidal activities of the target compounds were preliminarily evaluated. Some target compounds exhibited favourable antifungal activity at 50 mg/L. Myrtenal-derived 2-(p-methylbenzoyl)-1,2,4-triazole-3-thione (7i) held 83.7% and 72.5% inhibition rates against corn southern leaf blight (Bipolaris maydis) and apple root spot (Physalospora piricola), respectively, and myrtenal-derived 2-(3',5'-dimethylbenzoyl)-1,2,4-triazole-3-thione (7j) had 72.5% inhibition rate against P. piricola (the positive control commercial fungicide chlorothalonil with growth inhibition rates of 90.4% and 75.0% against B. maydis and P. piricola, respectively). Besides, most of the target compounds displayed excellent herbicidal activity against the root-growth of rape (Brassica. campestris). At 100 mg/L, 15 compounds held growth inhibition rates in the range of 80.2%~99.1%, exhibiting much better herbicidal activity than that of the commercial herbicide flumioxazin (positive control) with 63.0% growth inhibition rate.

Carbon dioxide as a green and cheap C1 synthon has significant research value and industrial application prospect. In recent years, using carbon dioxide to synthesize cyclic carbamates, quinazoline-2,4-(1H,3H)-diones, cyclic lactones and other heterocyclic compounds have been research hotspot. Many of the heterocyclic compounds can be synthesized by reacting the carbon atom in carbon dioxide with electron deficient with nucleophiles. This review focuses on the recent intermolecular and intramolecular reactions of carbon dioxide with nucleophiles centered around nitrogen, oxygen, or carbon.

Ph₂P (O)-deprotection/intramolecular Eglington coupling cyclization, proceeding in one-pot manner, can be applied to synthesize cyclic phenyl polyynes. Compared to Micheal M. Haley's stepwise desilylation/Eglington coupling reaction, the polar Ph₂P (O) protecting group enabled facile seperation of product from remaining starting compound for their different polarity, and it also led to easy separation of target compound because the amont of by-products which showed similar R_f to target compound decreased. Furthermore, our one-pot reaction, avoiding the workup after Ph₂P (O)-deprotection and reducing losses of materials, increased the yield of cyclic aromatic polyynes. This method showed some other outstanding features including easy synthesis of intermediates and mild reaction conditions.

Alanine triazole Mn-catalyzed 1,6-conjugate coupling/aromatization of para-quinone methides was developed with good to high yields under mild conditions. This protocol provided an efficient and practical route to the synthetically interesting functionalized methines and their analogues. Preliminary mechanistic experiments revealed 1,6-conjugate addition of nucleophiles to para-quinone methides (p-QMs). The manganese was acted as the Lewis acid.

Alkaline-earth-metal compounds have been widely concerned due to its abundant reserve and the low-cost. In recent years, alkaline-earth-metal catalysis has achieved great progress in dehydrocoupling, hydroboration, hydrophosphination, hydroamination, hydrosilylation reactions experimentally and therotically. These types of reaction and catalytic mechanism, leading to indentify the role of alkaline-earth-metal in hydrogenation and dehydrogenation reaction are summarized. These reactions, in which the metal-hydride act as active species, generally undergo the reaction pathway involving the cleavage and formation of the metal-hydride covalent bond. The reaction features and mechanisms are generally recognized accrossing to the classification and discussion of these reactions, which would provide guidance for further development of alkaline-earth-metal catalysis.

An intramolecular dinuclear zinc complex was used in asymmetric Friedel-Crafts alkylation of pyrrole with a wide range of chalcone derivatives. This dinuclear zinc complex was prepared in situ by reacting the chiral ligand (S,S)-1 with 2 equiv. of ZnEt₂. A series of β-pyrrole-substituted dihydrochalcones were formed mostly in excellent yields (up to 99%) and excellent enantioselectivities (up to >99% ee) by using 15 mol% catalyst loading under mild conditions. A possible mechanism was proposed to explain the origin of the asymmetric induction.

The difluoromethyl functional group (CF₂H) which has strong lipophilic and electron-withdrawing properties can significantly enhance the physiological activity of organic molecules. The applications of CF₂H-containing compounds in the fields of drugs, agrochemicals and so on have attracted great attention of many research groups. Therefore, the development of effective and general methodologies for the selective incorporation of difluoromethyl groups has become one of the hotspots in the field of organic chemistry. Recently, new difluoromethylation reagents and methods that were able to efficiently incorporate the difluoromethyl group under mild conditions have been developed rapidly, that pave the way for the facile introduction of difluoromethyl group into site-specific positions of the target molecules. In this paper, we will first briefly introduce some organic molecules with different functional groups which can be difluoromethylated, and then focus on the development of the recent high-performance difluoromethylation reagents, new reactions and catalysts. Finally, we will discuss the remaining problems and challenges in this particular field.

3,4-Fused indole alkaloids are an important part of naturally occurring indole alkaloids and have attracted considerable interests from synthetic chemists because of their unique structures and various biological activities. In this review, the recent total syntheses of the 3,4-fused indole alkaloids from 2013 are summerized and classified by the ring-closing positions of the indole 3,4-fused ring.

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.

Carbon monoxide is a readily available and cheap C1 feedstock. Carbonylation, the direct incorporation of carbon monoxide into organic molecules, is a very important and fundamental chemical transformation. In recent years, developing transition-metal-free systems for the carbonylation has attracted highly attention from many researchers. The recent rearch progress of transition-metal-free carbonylations for the synthesis of aldehydes, ketones, esters, amides, acids, anhydrides, acyl chloride, and alcohols is reviewed. And the development and application prospects for transition-metal-free carbonylation are also discussed.

A total of twenty novel 1, 2, 4-triazole-acylhydrazone derivatives containing the quinazolin-4-one moiety were synthesized via the condensation reaction of triazole hydrazide with various aromatic aldehydes, and fully characterized by ¹H NMR, ¹³C NMR and HRMS spectra. Antimicrobial assays in vitro indicated that most of the target compounds exhibited good antibacterial activities against the pathogenic phytobacteria Xanthomonas oryzae pv. oryzae(Xoo) and Xanthomonas axonopodis pv. citri(Xac). Notably, N'-(2-methoxybenzylidene)-1-(2-(4-oxoquinazolin-3(4H)-yl) ethyl)-1H-1, 2, 4-triazole-3-acylhy-drazone)(7q) displayed the inhibition rate of 100% against the above two bacteria at 100 μg/mL. Additionally, 1-(2-(4-oxo-quinazolin-3(4H)-yl) ethyl)-N'-(4-(trifluoromethyl) benzylidene)-1H-1, 2, 4-triazole-3-acylhydrazone (7i), N'-(2-bromobenzyli-dene)-1-(2-(4-oxoquinazolin-3(4H)-yl) ethyl)-1H-1, 2, 4-triazole-3-acylhydrazone (7j), N'-(4-bromobenzylidene)-1-(2-(4-oxo-quinazolin-3(4H)-yl) ethyl)-1H-1, 2, 4-triazole-3-acylhydrazone (7l), and N'-(4-methoxybenzylidene)-1-(2-(4-oxoquinazolin-3(4H)-yl) ethyl)-1H-1, 2, 4-triazole-3-acylhydrazone (7o) were found to possess the inhibition rate of >55% against the fungus Botrytis cinerea Pers. at 50 μg/mL.

Recently, transition metal-promoted trifluoromethylation has been developed rapidly. Starting with the types of transition metal that promote the trifluoromethylation reactions, the research progress of trifluoromethylation promoted by silver, iron, palladium, nickel, rhodium and cobalt in recent years is reviewed. Moreover, the possible mechanisms of some parts of reactions are also discussed.