As an important kind of organic chemical reaction, difunctionalization of alkenes can not only synthesize multi-site reaction products effectively in one step, but also transform the starting material into other compounds that containing biological activity or drug activity. At the same time, it provides more methods for the construction of chemical structure diversity, so it is very important to develop the bifunctionalization of alkenes. In this paper, the bifunctionalization of various alkenes in recent 12 years is reviewed. It can be divided into three parts:copper-catalyzed difunctionalization of alkenes, other transition metal-catalyzed difunctionalization of alkenes, and non-metal-catalyzed difunctionalization of alkenes. The prospects of this reaction are also discussed.

Reactive nitrogen and reactive oxygen are chemical substances with strong biological activity. In human cells, peroxides can be generated due to enzymatic or non-enzymatic processes. Abnormal levels of peroxide can cause oxidative damage and aging and various diseases such as cardiovascular disease, neurological diseases, Alzheimer's disease, Parkinson's disease and even cancer. In order to effectively cure these diseases, health workers must find the source of the problem. Currently, there is no better way to detect reactive oxygen species and reactive nitrogen. Fluorescence spectrometry in recent years becomes the preferred method for the majority of researchers for detecting active oxygen and reactive nitrogen. Therefore, the development of selective recognition and high sensitivity molecular fluorescent probes to achieve effective detection of reactive nitrogen and reactive oxygen species is of great significance. On one hand, molecular fluorescent probe detecting and imaging technology has excellent characteristics such as high sensitivity, strong selectivity, small damage and good cell compatibility. On the other hand, fluorescent probes play an important role in the pathophysiological process of reactive nitrogen and reactive oxygen species. Therefore, the fluorescent probe method is widely used in the fields of biology and medicine. However, due to the inherent specificity of reactive nitrogen and reactive oxygen species, it has become an urgent problem for researchers, such as high reactivity, short cycle, etc. In order to overcome the shortcomings of fluorescent probe analysis, researchers are constantly striving to find better active fluorescent probes for the detection of reactive nitrogen and reactive oxygen species. Recent evolutions in the development of molecular fluorescent probes for the detection of active nitrogen and reactive oxygen species and cell imaging work are reviewed. Finally, a new type of molecular fluorescent probe is proposed to be used for the challenge of active nitrogen and active oxygen detection, and the future development direction and prospect.

Axially chiral biaryl skeletons are ubiquitous stuctural motifs that are widely represented in pharmaceuticals and natural products, and have been widely used as privileged chiral ligands/catalysts in asymmetric synthesis. Therefore, the asymmetric construction of these compounds has received tremendous attention. However, the established strategies are mainly limited to the construction of biaryls containing hexatomic aromatics, and the approaches towards atropisomers featuring pentatomic heteroaromatics connected through C-C or C-N bond have emerged gradually only until recently. The main hurdle is basically due to the increased distance of substituents ortho to the axis, which is responsible for lower barriers to rotation, thus rendering the asymmetric synthesis more challenging. This review summarizes recent advances on the enantioselective synthesis of atropisomers featuring pentatomic heteroaromatics.

Imines are very important class of compounds and have been widely utilized in fine chemicals, pharmaceuticals and chemical industry. The C=N double bond in imine is an important nitrogen source in different types of reactions due to its high reactive activity. Due to its high atom economy, catalytic direct coupling of alcohols and amines to imines based on metal catalysts has attracted much attention and maken great progress in recent years. In this paper, the advances in direct coupling of alcohols and amines to imines catalyzed by metal catalysts are reviewed.

Carbazole and its derivatives are widely used in the field of medicine and photoelectric materials. A kind of stable cyclic hypervalent iodine reagents containing carbazole group was developed, which belong to benziodoxole compounds. In the presence of Cu(I) catalyst, these reagents reacted with aromatic substrates to give N-aryl carbazole derivatives. The reaction conditions are mild and suitable for a variety of electron-rich arenes. And a radical mechanism was proposed.

A novel method of copper-catalyzed cyclization of 1-aryl-1-cycloalcohols and 1,3-dicarbonyl compounds has been developed, affording various cycloalkane-fused dihydrofurans in moderate to excellent yields. This transformation proceeds under mild conditions and with a good tolerance of functional groups. The mechanistic investigation revealed that the reaction involved radical intermediates.

A phosphine-mediated Staudinger/Aza-Michael addition of azides with trifluoromethyl substituted α,β-unsaturated ketones was developed, giving hydroamination products in medium to good yields (up to 96%). The hydroamination products could be prepared on gram scale and a wide range of substrates are tolerated under the optimized reaction conditions (30 examples). ³¹P NMR experiments indicate that this reaction was initiated by Staudinger reaction of azide with phosphine.

A highly chemo-, regio-, and stereo-selective cobalt-catalyzed dehydrogenative silylation of vinylarenes was described. The imidazoline iminopyridine cobalt complex could promote this reaction effectively and improve the chemoselectivity dramatically. This protocol used earth-abundant transition metal, readily available alkenes and hydrosilanes to construct valuable vinylsilanes. The reaction could be carried out in gramscale and the proposed mechanism was also described.

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.

Heterocycles are ubiquitous in natural products, pharmaceuticals, organic materials, and numerous functional molecules. These structural units probably constitute the largest and most varied family of organic compounds. Hence the development of new procedures for heterocycles synthesis has been a hot research topic for over centuries. Among all the new synthetic methods, transition-metal-catalyzed reactions are attractive. Those reactions can formulate complicated heterocycles efficiently from available starting materials under mild conditions and atom economical routes. Among them, transition-metal-catalyzed carbonylation reaction has become an efficient and useful tool in organic synthesis since the first hydroformylation reaction developed by W. Reppe at BASF in the 1930s. Since then impressive progress has been achieved in this area. In nowadays, various types of carbonylation reactions were established. Substrates including aryl halides, olefins, alkynes or simply C-H bond can be activated and produce the corresponding carbonyl-containing compounds smoothly. On the other hand, carbon monoxide was discovered and identified in the 18th century. Since the first applications in industry around 80 years ago, academic and industrial laboratories have explored uses of CO in chemical reactions broadly. However, because of the special physical properties of CO, organic chemists were often reluctant to apply carbonylations frequently in laboratories. Hence, different kinds of CO surrogates were developed and applied in carbonylation reactions, such as metal carbonyl compounds M(CO) _x, formates, alcohols, formic acid, aldehyde, biomass and carbon dioxide. Those CO surrogates offer interesting opportunities for carbonylation reactions. This account mainly outlines our progress in the development of transition-metal-catalyzed carbonylative synthesis and functionalization of heterocycles from 2012 to 2018. With copper, palladium, rhodium, ruthenium and iridium as the catalysts and relying on the activation of carbon-halogen and carbon-hydrogen bonds, we are able to synthesis various of heterocycles by using CO gas or CO surrogates as the C1 building blocks.

Construction of C-N bond is one of the most important areas in synthetic organic chemistry and medical chemistry. Many synthetic methods for the construction of C-N bond have been reported over the past few years. Copper-catalyzed Chan-Lam reactions represent one of the most powerful and straightforward tools to construct C-N bonds. In this paper, the recent progress in Chan-Lam coupling of N-compounds with (hetero) aryl boronates to construct C-N bond based on the reaction mechanism, reaction system, the scope of substrates, etc., is reviewed.

Three series of chalcones bearing a piperidino, morpholino, and 1-methylpiperazino moiety were synthesized in two steps with the key step being Claisen-Schmidt condensation and tested for the activity against five cell lines, MCF-7 (human breast adenocarcinoma cell line), A549 (human lung adenocarcinoma epithelial cell line), HL-60 (human leukemia cell line), Hela (human cervical cancer cell line), and Bewo (human chorionic tumor cell line) by thiazolyl blue tetrazolium bromide (MTT) assay. Some chalcones exhibited good anticancer activity, and among them 4a, 4e, 4f, 4j, 4m, and 4o displayed the best anticancer activity for MCF-7 breast cancer cells, A549 lung cancer cells, and HL-60 leukemia cancer cells with IC₅₀ values below 10 μmol/L, respectively.

A novel palladium(0)-catalyzed dearomative spirocyclization reaction of bromophenols has been developed for building a series of spirocyclic architectures containing a quaternary carbon center via[2+2+1] strategy. This method employs inexpensive bromophenols and easily accessible alkynes. It exhibits a broad substrate scope in good yields. Notably, this transformation can be realized with high regioselectivity (>19:1 rr) when using unsymmetrical alkynes, which greatly expands the research scope of phenol dearomatization.

Organosilicon compounds play an important role in pharmaceutical chemistry, material science and organic synthesis. Transition-metal-catalyzed direct silylation of C-H bond, as one of the most concise and efficient methods for the synthesis of organosilanes, has developed rapidly in recent years. In this paper, the recent advance in transition-metal-catalyzed silylation of C-H bonds since 2015 is mainly reviewed.

o-Quinone derivatives are not only a variety of active and important intermediate, but also widely used in the synthesis of natural products and medicinal chemistry. In the present study, the Sc(Ⅲ) catalyzed aza-Michael addition to o-quinone methides by amines for the synthesis of Betti base derivatives was developed. The reaction was performed in a sealed tube at 90℃ for 4 h and the products were obtained in moderate to good yields (76%~96%).

An electrochemical synthesis of tetrasubstituted hydrazines through dehydrogenative dimerization of secondary amines has been developed. The reactions are conducted in a simple undivided cell with constant current. The use of electricity to promote the reactions obviates the need for transition metal catalysts and oxidizing reagents, providing an efficient and sustainable access to tetrasubstituted hydrazines with diverse electronic properties.

The development of efficient methods for the preparation of unnatural amino acids has long been an important goal since their widely application in synthetic and medicinal chemistry. The asymmetric α-functionalization of nucleophilic metalated azomethine ylides, which could be in situ-generated from readily-available aldimine esters, has been recogonized as a powerful strategy to synthesize unnatural amino acids. Over the past 20 years, tranistion metal-catalyzed asymmetric construction of unnatural amino acids using azomethine ylides have been extensively studied. In this review, the progress on metallated azomethine ylides invovled aymmetric transformation for the synthesis of unnatural amino acids is summarized according to eletrophilic reagents.

Fluorescence detection based on excited state intramolecular proton transfer (ESIPT) using reaction-based probes has attracted considerable attention in the scientific community as they offers promising advantages, including high selectivity, high sensitivity and large Stoke shift. The representative examples of design strategies, mechanism of actions, existing challenges and future developments for reaction-based ESIPT fluorophores reported in the last ten years are reviewed.

Baeyer-Villiger monooxygenase (BVMO) is an important biocatalyst for Baeyer-Villiger oxidation of various organic ketone/aldehyde compounds, and sulfur, selenium, or boron-containing heteroatoms compounds. As an indispensable tool, BVMO-catalyzed oxidation displays some advantages, such as high selectivity, mild reaction conditions and high efficiency, leading to wide applications into the synthesis of chiral compounds. In recent years, bioinformatics analysis and genome mining have been used to find more novel BVMOs from microorganisms. Besides natural substrates, these BVMOs can accept various organic compounds showing wide substrate scope. Meanwhile, protein engineering has been widely used to improve the catalytic performance of BVMOs, such as the expanded substrate scope, high thermostability and activity, high stereo-, regio-and chemo-selectivities. Based on the Baeyer-Villiger oxidation reaction with different substrate structures, the recent advancements in the research on the catalytic oxidation of wild type and protein-engineered BVMOs in the past five years are summarized.

Sodium sulfinates (RSO₂Na) is a kind of reagents with stable properties, simple synthesis and low price, which has been widely used in the field of organic synthesis chemistry. The recent progress (2014~2018) on synthesis of sulfur compounds by sodium sulfinates is summarized. In addition, the organic reactions on the building of S-X (S-S, S-N and S-P bond) and other types of reactions are described respectively, with their scope of substrates and reaction mechanism. It is hoped that this review can be referred to the future application in organic synthesis of sodium sulfinates.

Endoplasmic reticulum (ER) is an important organelle in eukaryotic cells and participates in the synthesis and secretion of various proteins, glycogen, lipids, and cholesterol substances. It is surrounded by a single membrane in the cytoplasm, which is a three-dimensional mesh structure formed by flat cysts, membrane tubes, and bubbles. Research on the physiological morphology of ER can facilitate the resolution of certain metabolic diseases. Due to the good optical properties and outstanding specific localization, fluorescent probe technology has been widely used in structural investigation and activity tracking of organelles. The ER fluorescent probes can be divided into two types, one is a single functional ER localization probe, the other is a multi-functional ER probe, which has multiple functions of locating and detecting active species in ER, the morphology and environment of ER. In this article, the structure, function and biological application of ER fluorescent probes in recent years are summarized and reviewed. Various localization mechanisms of ER fluorescent probes are described. The development trend of ER fluorescent probes in life science research is prospected.

Oxiranes are a class of oxygen-containing three-membered cyclic compounds. Due to their distinctive structure and unique properties, they can undergo a variety of cycloaddition reactions with compounds bearing diverse unsaturated bonds. The recent advances in the cycloaddition of oxiranes with this kind of compounds over the past decade, including[3+2],[3+3] and[4+3] are summarized. Moreover, the prospects of future development are also discussed.

Sulfhydryl compounds, such as cysteine (Cys), homocysteine (Hcy), glutathione (GSH) and so on, play an important role in the normal human physiological processes. Molecular fluorescent probes have attracted much attention of scholar in the detection of sulfhydryl compounds, since it has the advantage of good selectivity, high sensitivity, good biocompatibility and real-time in situ monitoring. At present, the design of thiol-based fluorescent probes is mainly based on the strong nucleophilicity of sulfhydryl groups. In this paper, the synthesis of fluorescent probes for detecting sulfhydryl compounds, which was reported from 2013 to 2018, is reviewed based on the different mechanism of the reaction between fluorescence probe and sulfhydryl, including Michael addition, cyclization of aldehyde groups, sulfonamides or sulfonates of the lysis, natural chemical linkage and so on. The detection limit of the probe, response time, equivalence ratio were elaborated.

The phosphine-catalyzed[3+2] annulation of γ-methyl allenoates with 2-arylidene-1H-indene-1,3(2H)-diones is reported. In the reaction, a series of highly functionalized spiro[4.4]dec-6-ene skeletons were obtained in moderate to good yields and high diastereoselectivities. It should be noted that the perfect α-regioselective annulation adducts were obtained with simple PPh₃ catalyst.

Organic molecules containing trifluoromethyl groups often exhibit unique physical and chemical properties, and have found extensive applications. Trifluoroacetic acid and its derivatives have advantages including low cost, ready availability and high stability. Furthermore, CO₂ is the byproduct. Therefore, trifluoroacetic acid and its derivatives are ideal trifluoromethylating reagents, and have great application potentials. The progress of trifluoromethylation reactions using trifluoroacetic acid and its derivatives as CF₃-sources is reviewed, including the reactions of C-X (X=Br and I), C-H, and C=X (X=C, O). The mechanisms are also introduced.

Twelve new piperdine thiazole compounds were designed and synthesized in search of new bioactive compounds. The preliminary bioassay showed that at the concentration of 500 μg/mL the lethal rates of the target compounds possessed certain insceticidal activities against armyworm, and at the concentration of 100 μg/mL the lethal rates of (4-(5-(3-chloro-phenyl) -4-methylthiazol-2-yl) piperidin-1-yl) (4-methylpiperazin-1-yl) methanone (1f) and (4-(5-(4-chlorophenyl) -4-methyl-thiazol-2-yl) piperidin-1-yl) nitro-1H-pyrazol-3-yl) methanone (1g) against armyworm were 80% and 100%, respectively. Further screening at concentrations of 20 μg/mL, the lethal rate of (4-(5-(4-chlorophenyl) -4-methylthiazol-2-yl) piperidin-1-yl) (4-nitro-1H-pyrazol-3-yl) methanone (1g) against armyworm was 50%.

NS5 is a protein component which plays a main role in replication of Zika virus, and its component part-methyl-transferase (5M5B) is the central participants of virus replication and host innate immune response. So it is used as the preferred protein of potential antiviral drugs development. Using 5M5B as receptors and using its binding sites to screen with over 2 million small molecule compounds, the leading compounds of anti-Zika virus were obtained. The structural optimization, activity prediction, chemical synthesis and pharmacological activity of the leading compound were studied. All the synthesized compounds were characterized by ¹H NMR and ¹³C NMR. The antiviral activity of compound 3a is better than that of ribavirin (IC₅₀=(7.69±0.36) μmol·L^-1 for 3a vs IC₅₀=(8.15±0.42) μmol·L^-1 for ribavirin).

Amide motifs are prevalent structures found in natural products, pharmaceuticals, and bioactive compounds. Amide bond formations are the most important transformations in organic chemistry. Beckmann rearrangement is a significant method for the synthesis of primary and secondary amides. Recently, diversified new catalytic protocols were developed, including one-pot reaction from the corresponding aldehydes and ketones, or even from alcohols. The progress and applications of Beckmann rearrangement in recent five years are reviewed.

Asymmetric hydroformylation is one of the most important reactions for preparation of chiral aldehydes from alkenes. Recently, significant progress has been made in this field and a series of new ligands have been developed. Asymmetric hydroformylation of several important alkenes has been achieved, offering efficient and concise methods for the synthesis of chiral aldehydes. In this review, the achievements of asymmetric hydroformylation of typical alkenes and the development of ligands for asymmetric hydroformylation are summarized.

Scientists have found more and more sulfur compounds in food with the development of science and technology, high-precision analytical methods and equipment. In 2015, Flavor and Extract Manufactures Association of the United State published 2816 safe flavors, and there are more than 388 sulfur-containing compounds, accounting for more than 13%. The main smell of sulfur-containing flavors is food, especially the non-staple food and dishes. It is mainly used as food flavor, flower flavor and fruity flavor. Due to the increase of sulfur-containing perfume and flavors demand, its production scale is increasing, the research on synthesis methods is also deepening, and the green and efficient construction methods are also constantly reported. In this review, the recent progress in the construction of sulfide, thiol, thioester and polysulfide perfume & flavors is summarized.

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.

Alkaline-earth metals continue to receive growing interest, as they are used as low-cost and non-toxic alternatives to transition-metals in various organic transformations. As ionic character and bond lengths increase along the row in the order Mg²⁺2+2+2+, bond energies decrease along the same row, the corresponding metal hydrides are apt to the formation of insoluble metal hydrides[AeH₂]_∞ (Ae=Mg, Ca, Sr, Ba) through Schlenk equilibrium in solution. Recently, a series of alkaline-earth metal hydrides stabilized by suitable ligands were discovered and characterized, and stoichiometric and catalytic reactions with small molecules were studied as well. In this paper, the recent progress in molecular alkaline-earth metal hydrides is reviewed.

Quinoxalin-2(1H)-ones are very important N-heterocyclic moieties found in natural products and pharmaceuticals, and exhibit an amazingly wide spectrum of biological properties. Numerous efforts have been devoted to the development of efficient approaches for the C-H bond activation and functionalization of quinoxalin-2(1H)-ones in recent years, including alkylation, benzylation, acylation, arylation,amination, amidation, phosphonation, and fluoroalkylation. The recent advances in this area are summarized and their reaction mechanisms are discussed.

Compared with traditional chemical catalysis or enzymatic synthesis, chemoenzymatic relay reaction is a simpler, more efficient and economical method. It not only has the advantages of high efficiency and selectivity of enzyme catalysis, but also has the advantages of low price of synthetic raw materials, simple and high efficiency of synthetic process, green and friendly production environment, and excellent optical purity of the obtained product. Thus, chemoenzymatic relay synthesis methods have been widely used in the synthesis of high-value chiral compounds. In recent years, chemists have been committed to making chemoenzymatic catalytic conditions easier by changing catalysts and designing more reasonable ways, which could be used in more fields. In this review, the recent progress in the synthesis of chiral alcohols, epoxides, heterocyclics and other chiral compounds by using chemoenzymatic relay synthesis, such as enzyme and metal catalysis, enzyme and organic catalysis, enzyme and new reaction techniques, is reviewed, and the development trends of this field are also prospected.

The synthesis of the AC ring moiety of daphnilactone B has been achieved through an efficient Diels-Alder reaction and Au-catalyzed Conia-ene reaction in seven steps with 30% overall yield. Our strategies paved the way to the total synthesis of various daphnilactone B-type Daphniphyllum alkaloids.

Heterocyclic compounds are widely applied in medicine, fine chemical engineering and the related industrial fields. Consequently, the development of efficient strategies for heterocycle constructions continues to be of great appeal in organic synthesis. In recent years, the I₂-catalyzed direct C-H bond functionalizations have emerged as one of the most efficient synthetic protocols to construct diverse heterocycles. In this review, the recent advances in I₂-catalyzed C-H bond functionalizations by the types of C-C and C-N/O/S bond formations are summarized, and an outlook of this research filed is given.