In addition to the four canonical nucleobases of A, G, T and C, hundreds of chemical modifications have been identified in genome DNA. Among them, 5-formylpyrimidines, including 5-formylcytosine(5fC) and 5-formyluracil(5fU), are naturally occurring pyrimidine-covalent-modifications and are widely distributed in mammalian cells. Emerging evidence indicates that 5fC not only serves as a key intermediate in active DNA demethylation but also carry independent epigenetic significance; while 5fU was always considered to be an oxidative DNA lesion with high genotoxicity. In order to further understand their regulatory functions, it is necessary to develop accurate, sensitive and facile methods for qualitative, quantitative, and localized detection of 5-formylpyrimidines in the whole genome. In this review, we summarized the recent progress in detecting 5-formylpyrimidines from the perspective of selective chemical labeling.

Crown ethers, as the first generation macrocycle, with flexible cavity, are widely used to construct supramolecular assemblies, due to their complexation of metal ions and organic cations. Sulfonated crown ether is a kind of anionic crown ether derivative with good water solubility, compared with crown ether, it possess more binding sites, stronger binding ability and better guest selectivity with metal ions and organic cations. This review introduces the research progress of sulfonated crown ether from the synthesis of sulfonated crown ethers, the complexation of alkali metal ions, lanthanide metals, and the assembly of organic cationic guests. Then we comprehensively analyse the binding modes and driving forces of sulfonated crown ethers from the perspectives of thermodynamics and crystal structures. Finally, we discuss the opportunities and challenges of the development of molecular binding and assembly of sulfonated crown ethers, and prospected the application of sulfonated crown ethers.

It has been established that hydrophobicity, hydrogen bonding, electrostatic attraction, halogen bonding and coordination all can be utilized to stabilize the folding and/or helicity of aromatic macromolecules and supramolecular systems. The resulting aromatic helical tubes possess defined diameters and tunable depth and can be used as synthetic receptors for recognizing or encapsulating a variety of guest species, achieving chirality induction and transfer, promoting organic transformations, and as artificial channels for transmembrane transport. This review highlights the advance in the construction of such family of macromolecular and supramolecular tubes from aromatic segments and their important functions. In the first section, we introduce the background of the formation of tubular structures from different strategies and the features of the supramolecular and macromolecular approaches. We then highlight the formation of molecular tubes from various oligomeric molecules with aromatic amide, hydrazide, triazole and ethyne repeat segments. In the following section, we describe the use of polymeric backbones with the above repeat segments. The self-assembly strategy for the formation of supramolecular tubes is then summarized in another section. In particular, the utility of hydrogen bonding, halogen bonding and coordination interactions has been described. When available, the functions of the tubular structures are briefly presented. In the last section, we discuss the synthetic challenges for the formation of long macromolecular tubes and the new potential applications of this family of structurally unique structures.

In this review, the synthesis and application of a series of tridentate ligands, such as f-amphox, f-ampha, f-amphol and f-amphamide, bearing ferrocene skeleton are introduced. The corresponding iridium complex based on these chiral P-N ligands can catalyze(functionalized) ketones with high TON(up to 1 000 000), excellent conversion(>99%) and enantioselectivity(>99% ee). The application of the f-series ligands has successfully realized the asymmetric synthesis of many chiral pharmaceutical intermediates such as Dinopramine, Phenylephrine and Salbutamol. These approaches are more efficient, generating less by-products and lower industrial emissions compared with the traditional routes.

The effective use of CO₂ has become a research hotspot worldwide, whose excessive emission led to increasingly serious global environmental problems. Compared with high energy-consuming CO₂ capture and storage(CCS) technology, the photocatalytic conversion of CO₂ into a valuable energy fuel is an effective way to solve energy and environmental problems. Among them, the development of a photocatalyst with efficient catalytic performance under visible light is the key to this process. Currently, there are still many shortcomings in photoreduction CO₂ catalysts, such as weak visible light response ability, high recombination rate of photo-generated electron-hole pairs, low CO₂ adsorption capacity, poor product selectivity, and hydrogen-evolution competition in an aqueous environment. Metal-organic frameworks(MOFs), with adjustable porous structures, fast electron migration rate, large CO₂ adsorption capacity, etc., are a unique class of porous crystalline materials composed of metal ions/clusters and organic ligands, which have broad application potential in CO₂ photocatalytic reduction. The existing methods improving the catalytic performance of MOFs-based catalysts is mainly to enhance the absorption of visible light by functional modification, formation of composites with other functional materials and so on. This review mainly analyzes and discusses the recent advances of MOFs-based photoreduction CO₂ catalysts(single MOFs, MOFs-based composites and MOFs-derived materials), and predicts future development trends and prospects of MOFs-based materials in photocatalytic reduction of CO₂.

Pyrazolin-5-one compounds play an important role in bioactive compounds and have attracted extensive attention. Pyrazolin-5-one and its common derivatives have many reaction sites and can participate in a variety of asymmetric reactions, such as asymmetric addition reactions, asymmetric annulation reactions and other asymmetric reactions. In this context, we summarize the recent progress in asymmetric reactions of pyrazolin-5-one and its common derivatives. The main reaction types involving the pyrazolin-5-one compounds are classified, and their main reaction sites are expounded. Finally, the challenges and development of pyrazolone derivatives are summarized, and the future development direction is prospected.

Since L-prolinamide was revealed to have high capacity to catalyze asymmetric aldol reaction, great advances have been made on the design of chiral amino amide catalysts and their applications in asymmetric catalysis. In particular, the “enamine-double hydrogen-bonding activation mode” has turned out to be a general concept for the proliferation of structurally diverse range of organocatalysts. This review mainly describes asymmetric reactions catalyzed by chiral amino amides containing single hydrogen-bonding donor, double hydrogen-bonding donors and multiple hydrogen-bonding donors, including enantioselective direct aldol reaction, Mannich reaction, Michael addition reaction, cycloaddition reaction, tandem cyclization reaction, Biginelli reaction and others.

As an important unit of molecular structure and organic building blocks, the development of new synthetic methods of allene has received much attention. The Heck and related cascade reaction of alkenes is arguably one of the most synthetically versatile method. However, the Heck reaction of alkyl-alkynes leading to allenes has lagged behind due to the energetically unfavored β-hydride elimination of vinyl palladium species. Several competitive reactions such as protonation, carbohalogenation and cascade reaction exist. Moreover, the isomerization of allene and the regioselectivity of unsymmetrical alkyl-alkynes also limited this research progress. To effectively promote β-hydride elimination of vinyl palladium species, several commonly-used strategies are the increasing reaction temperature, introduction of ortho-substituent to aryl halides and the development of ligand. In this mini-review, Heck and related reaction of alkyl-alkynes including β-hydride elimination reactions of vinyl palladium species, protonation reaction, carbohalogenation reaction, and cascade reaction are emphasized. Finally, the major limitation and an outlook this type of reaction are provided.

Quinoproteins are an important type of redox enzymes for the oxidative metabolism of alcohols and amines, which employ ortho-quinones as the cofactors. On the basis of catalytic principles and strategies of quino-enzymes, a number of molecular quinone catalysts have been developed during the past two decades. With copper amine oxidases(CuAOs) as a blueprint, small molecular ortho-quinone catalysts have been developed for amine oxidation. These catalysts could mimic the catalytic performance of CuAOs, and expand the substrate scope to α-branched primary amines, secondary amines and tertiary amines. Recent studies have also uncovered a new type of quinoproteins, methanol dehydrogenase(MDH), utilizing rare earth elements as the active metal. In this review, we summarize the major types of quinoproteins, the development of their mimics ortho-quinone catalyst as well as perspective on the future development of bio-inspired ortho-quinone catalysis.

1,10-Phenanthroline and its derivatives, classic bidentate N-donor ligands, can form stable complexes with a variety of transition metals and have been widely used as catalysts in various organic reactions. Ferritic elements(iron, cobalt, nickel) have the advantages of high natural abundance, low cost, low toxicity and unique catalytic performance. The complexes of 1,10-phenanthroline type ligands and ferritic elements are ideal alternative catalysts. In recent years, 1,10-phenanthroline type ligands have been widely used in Fe/Co/Ni-catalyzed organic reactions,especially in cross-coupling reactions, addition reactions,and redox reactions,showing unique ligand effects. More and more studies revealed that the rigid aromatic structure of 1,10-phenanthroline plays an important role in improving the stability of the catalyst, and the substituents of 1,10-phenanthroline have a significant impact on the activity and selectivity of corresponding catalyst. More interestingly, a few recent studies disclosed that 1,10-phenanthroline ligands might change the spin state and three-dimensional electronic structure of the Fe/Co/Ni catalysts, which accounts for their unique reactivity as well as selectivity.Although with the above-mentioned progresses, there are still several important challenges in this field, including the poor structural diversity of 1,10-phenanthroline type ligands and poor understanding of the electron effect of 1,10-phenanthroline ligands to corresponding metal catalysts.In this review, we summarized the applications of 1,10-phenanthroline ligands in Fe/Co/Ni-catalyzed organic reactions, and gave an outlook of this promising field.

Carbohydrates are the most abundant organic compounds in nature, which play essential roles in the fields of medicine, materials, energy and environment. Due to the specific characteristic of high polarity, sophisticated structure and microheterogeneity, it is particularly difficult to separate, purify and synthesize carbohydrates. At present, the acquirement of carbohydrate compounds with homogeneous and diverse structures and in high purity mainly depends on chemical synthesis. However, the effective synthesis of carbohydrates has become a bottleneck of restricting the progress of glycoscience. The development of new methods and strategies for the synthesis of carbohydrates is the core topic in carbohydrate chemistry. The reaction driven by photon/electron energy usually takes place under mild conditions, which meets the requirements of green chemistry and sustainable development, and is also one of the research frontiers in modern organic synthesis. Nowadays, with the development of photo-/electro-synthetic technology, many achievements have been made in carbohydrate-based reactions driven by photon/electron energy. In view of reaction type, mechanism and status, this review will systematically summarize the latest advances on photo-/electro-driven reactions in the synthesis of carbohydrates. This review will also analyze the current challenges and new opportunities of carbohydrate-based reactions driven by photon/electron energy.

The synthesis of fused heteroaromatics is an important research area in organic chemistry and it has significant implications on the investigations of organic optoelectronic materials and devices. C—H bond is one of the most ubiquitous chemical bonds in organic compounds. The direct construction of fused heteroaromatics via the C—H bond cleavage and direct functionalization features concision and high efficiency, which could solve the limitations on the substrate preparation and product structural diversity in conventional synthetic methods. In this account, we review our works on the construction of fused heteroaromatics based on chelation-assisted transition metal-catalyzed oxidative C—H/C—H cross-coupling between(hetero)arenes/intramolecular cyclization during the past six years, including a comprehensive discussion of the features, advantages and reaction mechanisms of these reactions, and the applications of these strategies in the exploration of novel organic optoelectronic materials. Finally, the existing problems and development prospect of this area are elaborated.

Carbon allotropes comprised exclusively of sp² hybridized carbon atoms present flat or curved surface, whose overall geometric feature is reflected by its curvature. Consisting of six-membered rings exclusively, graphene has zero curvature. Five-membered rings induce positive curvature as displayed in fullerenes; while seven- or eight-membered rings in a hexagonal lattice of carbon induce negative curvature as displayed in a saddle-shaped surface. Negatively curved nanocarbons of three-dimensional periodic structures are named as Mackay crystal or carbon schwarzites, which are a long-sought target in carbon nanoscience, but have not been synthesized unambiguously yet. A bottom-up approach to negatively curved nanocarbons involves synthesis of negatively curved polycyclic arenes, which can then be used as templates or monomers in synthesis of larger nanocarbons. Negatively curved polycyclic arenes, which can be designed and synthesized by introduction of seven or eight-membered rings into polycyclic aromatic frameworks, exhibit structural characteristics and properties that are not available to planar polycyclic arenes. Taking the polycyclic arenes containing eight-membered rings as examples, this review article describes research in the design, synthesis, stereochemical dynamics, and other characteristics of negatively curved polycyclic arenes, and provides an outlook for new directions in the research of negatively curved nanocarbons.

Building block-approach is one of the basic strategies used by nature in biogenetic synthesis. Naturally occurring L-α-amino acids, L-α-hydroxy acids, D-mono-sugars, and terpenes, being cheap and easily available in enantiopure forms, have found widespread applications enantioselective synthesis as chiral building blocks. L-Malic acid, an L-α-hydroxy diacid, is a readily available and cheap natural chiron, D-malic acid is also commercially available although it is more expensive. With all of the four carbon atoms transformable or functionalizable, malic acid serves as a versatile C₄ building block in organic synthesis for enantioselective synthesis. In this review, the progress in the applications of malic acid in organic synthesis is summarized. Firstly, the transformations of malic acid into a variety of advanced chiral C₄ building blocks are compiled. Secondly, selected examples on the applications of these versatile intermediates in the total synthesis of complex natural products in recent years are presented. Besides, the developments of malic acid-based new synthetic methodologies including the contribution from one of the authors’ laboratory are highlighted. An outlook for future development of malic acid-based synthetic strategy is provided.