On-Surface Synthesis of Cumulene-Containing Polymers via Two-Step Dehalogenative Homocoupling of Dibromomethylene-Functionalized Tribenzoazulene

Cumulene compounds are notoriously difficult to prepare and study because their reactivity increases dramatically with the increasing number of consecutive double bonds. In this respect, the emerging field of on-surface synthesis provides exceptional opportunities because it relies on reactions on clean metal substrates under well-controlled ultrahigh-vacuum conditions. Here we report the on-surface synthesis of a polymer linked by cumulene-like bonds on a Au(111) surface via sequential thermally activated dehalogenative C−C coupling of a tribenzoazulene precursor equipped with two dibromomethylene groups. The structure and electronic properties of the resulting polymer with cumulene-like pentagon–pentagon and heptagon–heptagon connections have been investigated by means of scanning probe microscopy and spectroscopy methods and X-ray photoelectron spectroscopy, complemented by density functional theory calculations. Our results provide perspectives for the on-surface synthesis of cumulene-containing compounds, as well as protocols relevant to the stepwise fabrication of carbon–carbon bonds on surfaces.     

On‐Surface Synthesis of Cumulene‐Containing Polymers via Two‐Step Dehalogenative Homocoupling of Dibromomethylene‐Functionalized Tribenzoazulene

Cumulene compounds are notoriously difficult to prepare and study because their reactivity increases dramatically with the increasing number of consecutive double bonds. In this respect, the emerging field of on‐surface synthesis provides exceptional opportunities because it relies on reactions on clean metal substrates under well‐controlled ultrahigh‐vacuum conditions. Here we report the on‐surface synthesis of a polymer linked by cumulene‐like bonds on a Au(111) surface via sequential thermally activated dehalogenative C?C coupling of a tribenzoazulene precursor equipped with two dibromomethylene groups. The structure and electronic properties of the resulting polymer with cumulene‐like pentagon–pentagon and heptagon–heptagon connections have been investigated by means of scanning probe microscopy and spectroscopy methods and X‐ray photoelectron spectroscopy, complemented by density functional theory calculations. Our results provide perspectives for the on‐surface synthesis of cumulene‐containing compounds, as well as protocols relevant to the stepwise fabrication of carbon–carbon bonds on surfaces.     

能源催化材料的电化学合成

电催化是发展可持续洁净能源技术的基础科学,是电化学能源转换和物质转化的关键环节.精准合成催化活性纳米结构是制约很多电催化反应走向实际应用的重要挑战.与湿化学合成、固相合成和气相沉积等传统方法相比,电化学合成是一种简单、快速、廉价及可控的高效催化材料制备方法,也是一种最为直接的一体化电极制备方法.本文综述了近年来利用电化...     

Toward high-throughput synthesis of complex natural product-like compounds in the genomics and proteomics age

In the age of high-throughput biology, novel genes and proteins are emerging quickly. The need for developing organic synthesis-derived methods that allow rapid access to polyfunctional, complex natural product-like compounds is growing constantly, largely because these small-molecule-based compounds serve as smart, powerful tools both in understanding the roles and functions of emerging biological targets and in validating their biological responses. Developing asymmetric synthesis-derived organic reactions on solid phase allows the synthesis of complex natural product-like compounds in a high-throughput manner. Solid phase organic synthesis is now commonly utilized in the library synthesis of rather simple compounds (i.e., compounds with no multiple stereogenic centers). With few exceptions, the synthesis of complex natural product-like derivatives is still in its infancy. Some recent efforts made in this area indicate opportunities yet to be explored.     

Research progress of tunnel-type sodium manganese oxide cathodes for SIBs

Among the large energy storage batteries, the sodium ion batteries（SIBs） are attracted huge interest due to the fact of its abundant raw materials and low cost, and has become the most promising secondary battery. Tunnel-type sodium manganese oxides（TMOs） are industrialized cathode materials because of their simple synthesis method and proficient electrochemical performance. Na_0.44MnO₂（NMO） is considered the best candidate material for all tunnel-type structural materials. ...     

Nitrogen heterocycles as potential monoamine oxidase inhibitors: Synthetic aspects

The present review highlights the synthetic methods of monoamine oxidase inhibitors (MAO) belonging to a group of nitrogen heterocycles such as pyrazoline, indole, xanthine, oxadiazole, benzimidazole, pyrrole, quinoxaline, thiazole and other related compounds (1990–2012). Moreover, it emphasizes salient findings related to chemical structures and the bioactivities of these heterocycles as MAO inhibitors. The aim of this review is to find out different methods for the synthesis of nitrogen containing heterocycles and their bioactivity related aspects as MAO inhibitors.     

Distinctive features and challenges in catenane chemistry

From being an aesthetic molecular object to a building block for the construction of molecular machines, catenanes and related mechanically interlocked molecules (MIMs) continue to attract immense interest in many research areas. Catenane chemistry is closely tied to that of rotaxanes and knots, and involves concepts like mechanical bonds, chemical topology and co-conformation that are unique to these molecules. Yet, because of their different topological structures and mechanical bond properties, there are some fundamental differences between the chemistry of catenanes and that of rotaxanes and knots although the boundary is sometimes blurred. Clearly distinguishing these differences, in aspects of bonding, structure, synthesis and properties, between catenanes and other MIMs is therefore of fundamental importance to understand their chemistry and explore the new opportunities from mechanical bonds.

Catenane chemistry is closely associated with that of rotaxane and knot, and this perspective highlights their similarities and differences in various aspects including synthesis, structure and properties.     

Design and Synthesis of Powerful Capsule Catalysts Aimed at Applications in C1 Chemistry and Biomass Conversion

Tandem catalytic reaction is a promising strategy to improve the utilization efficiency of energy and resources. The conventional hybrid catalysts cannot readily realize the precisely controlled synthesis of target products due to the unrestricted, open reaction environment. Assembling the hybrid catalyst with multiple active sites into core‐shell structured capsule catalyst is one of the most effective ways to enhance the selectivity of desired products during a tandem catalysis process, because the core‐shell structure offers a space‐confined reaction field and synergistic effect. This review describes our recent progresses on the design and synthesis of core‐shell structured zeolite capsule catalysts developed for C1 chemistry and biomass conversion. The various synthesis methods for constructing the well‐defined zeolite capsule catalysts are described in detail. The applications of the capsule catalysts in catalysis, including the middle isoparaffins synthesis from syngas, one‐step synthesis of dimethyl ether, and liquid‐phase tandem reaction of glycerol conversion, are discussed, respectively. Our perspectives regarding the challenges and opportunities for future research in the field are also provided.     

The Baylis-Hillman reaction: a novel source of attraction, opportunities, and challenges in synthetic chemistry

The Baylis-Hillman reaction is a successful, useful, and atom-economical carbon-carbon bond forming reaction, which has grown from an obscure level to the level of high synthetic popularity due to its operational simplicity and also due to the enormous applications of the Baylis-Hillman adducts in organic synthesis. In this tutorial review, we briefly describe the way this reaction has grown to its present heights and the opportunities, attractions, and challenges the reaction offers with respect to its asymmetric and intramolecular versions, and mechanistic aspects.     

Enantioselective Chemo- and Biocatalysis: Partners in Retrosynthesis

Recent developments of stereoselective biocatalytic and chemocatalytic methods are discussed. The review provides a guide to the use of biocatalytic methods in the area of chemical synthesis with focused attention on retrosynthetic considerations and analysis. The transformations presented are organized according to bond disconnections and attendant synthetic methods. The review is expected to lead to better understanding of the characteristics and distinctions of the two complementary approaches. It depicts for researchers in bio- and chemocatalysis a road map of challenges and opportunities for the evolution (and at times revolution) in chemical synthesis.     

多力响应基团聚合物合成的研究进展

多力响应基团聚合物(MMPs)的设计与合成为高灵敏地观察和定量力化学转变及高效利用机械能提供了新机遇, 推动了聚合物力化学的发展. 本文主要介绍了后聚合改性、 逐步聚合、 开环易位聚合和活性/可控自由基聚合等4种MMPs的合成方法, 分别对这些方法的特点、 优势和适用体系进行了论述, 期望为新型机械力响应性聚合物的制备和应用提供新思路.     

Recent advances in mechanochemical C–H functionalization reactions

The mechanochemical synthesis has provided a greener alternative to solution-based approaches by eliminating the use of organic solvents and reducing the energy consumption. The C–H functionalization is among the most concise and economical synthetic strategies. The combination of the benefits from these two methods provides new opportunities to further increase the efficiency and sustainability of organic synthesis. In this digest, we aim to provide a brief overview of the recent advances in mechanochemical C–H functionalization reactions.     

Recent advance in synthesis and application of heteroatom zeolites

Incorporation of heteroatoms into the framewo rk of zeolites has become a significant strategy to improve their performance in catalysis and adsorption,because the obtained heteroatom zeolites exhibit quite different properties from the conventional aluminosilicate zeolites in aspects of surface acidity,pore structures,particle size and so on.In this review,the progress on the heteroatom zeolites including their synthesis and application is highlighted.First,the recent advance on the design and synthesis of different heteroatom zeolites is summarized.Special emphasis is placed on the introduction and comparison of three typical methods,including the direct synthesis,post synthesis and improved direct synthesis,for the traditional heteroatom zeolites(such as TS-1,Sn-MFI,Sn-β) and newly-reported heteroatom zeolites(such as W-MFI,Mo-MFI).According to their intrinsic characteristics,the application of heteroatom zeolites in diverse fields,such as production of fine chemicals,air pollution control and biomass conversion is then discussed.Finally,the challenges and perspective on the future development of heteroatom zeolites in low-cost preparation and practical application are proposed.     

Carbon–sulfur bond formation via photochemical strategies: An efficient method for the synthesis of sulfur-containing compounds

The development of green and convenient methods for C–S bond formation has received significant attention because C–S bond widely occurs in many important pharmaceutical and biological compounds.Recently, visible-light photoredox catalysis has been established as an efficient and general tool for the construction of C–C and C-heteroatom bonds. In this review, we have focused on the research on recent advances in C–S bond formation via visible-light photoredox catalysis, and the growing opportuni...     

Approaches to dihydrooxazine ring systems and application in the synthesis of bioactive natural products

This review describes selected approaches to the synthesis of 4H-5,6-dihydro-1,2-oxazines and application of these methods to the synthesis of natural products containing this heterocyclic ring system. The focus is on applications and on interesting aspects of chemistry related to this subclass of natural products, as well as newer methods for the synthesis of oxazines.     

Sequenced click chemistry and photopolymerization: a new approach toward semi‐interpenetrating polymer networks

Multi‐step curing systems involving photopolymerization are of great interest because they provide easy tunable properties and processes for polymer synthesis. Herein, new perspectives are proposed to form semi‐interpenetrated polymer networks through a versatile process involving two orthogonal chemistries. The sequence of reaction has been designed as follows: (i) a stoichiometric aza‐Michael addition between acrylates and amines in a methacrylate medium and (ii) ultraviolet curing of methacrylates. According to the structure of amine, this method affords the production of either mixed networks or semi‐interpenetrated polymer networks. Finally, it is shown that divinylsulfone can be used instead of acrylate, granting many opportunities to develop multifunctional materials with diverse and varied properties. Copyright © 2016 John Wiley & Sons, Ltd.     

Microwave-assisted synthesis of small molecules targeting the infectious diseases tuberculosis, HIV/AIDS, malaria and hepatitis C

The unique properties of microwave in situ heating offer unparalleled opportunities for medicinal chemists to speed up lead optimisation processes in early drug discovery. The technology is ideal for small-scale discovery chemistry because it allows full reaction control, short reaction times, high safety and rapid feedback. To illustrate these advantages, we herein describe applications and approaches in the synthesis of small molecules to combat four of the most prevalent infectious diseases; tuberculosis, HIV/AIDS, malaria and hepatitis C, using dedicated microwave instrumentation.     

Analysis of residual products in triethylbenzylammonium chloride by HPLC. Study of the retention mechanism

The control of industrial products for minimization of their impact on the environment and human health requires the development of specific analysis methods. Information provided by these methods about toxic components, by-products, and other derivatives may also be useful to reduce the possible impact of industrial products. The studied compound in this paper, triethylbenzylammonium chloride (TEBA), is mainly used in industrial synthesis. This quaternary compound and its residual products coming from quaternization reaction (benzyl chloride, benzaldehyde, and benzyl alcohol) are analyzed by HPLC. The separation is based on control of the silanophilic contribution to TEBA retention because of the quaternary nature of this compound. The effect of the three buffers (sodium acetate, ammonium acetate, and sodium formate) and their concentrations in the chromatographic behavior of the quaternary compound is examined. The buffer cation and anion regulate TEBA retention. Also, the concentration of the quaternary compound is another parameter that had influence in some aspects of its chromatographic behavior (e.g., retention and symmetry). The proposed method is applied to TEBA synthesis along, with the formation and removal of impurities with the results compared with those obtained for the quaternary compound benzalkonium chloride.     

Exploring Diradical Chemistry: A Carbon‐Centered Radical May Act as either an Anion or Electrophile through an Orbital Isomer

Diradical intermediates, formed by thermolysis of alkynylcyclobutenones, can display radical, anion, or electrophilic character because of the existence of an orbital isomer with zwitterionic and cyclohexatrienone character. Our realization that water, alcohols, and certain substituents can induce the switch provides new opportunities in synthesis. For example, it can be used to shut down radical pathways and to give access to aryl carbonates and tetrasubstituted quinones.     

Catalytic Enantioselective Isocyanide-Based Reactions: Beyond Passerini and Ugi Multicomponent Reactions

The development of catalytic enantioselective isocyanide-based reactions is currently of great interest because the resulting products are valuable in organic synthesis, pharmacological chemistry, and materials science. This review assembles and comprehensively summarizes the recent achievements in this rapidly growing area according to the reaction types. Special attention is paid to the advantages, limitations, possible mechanisms, and synthetic applications of each reaction. In addition, a personal outlook on the opportunities for further exploration is given at the end.