壳聚糖负载贵金属催化剂的研究进展

壳聚糖负载的贵金属催化剂显示了高催化活性和高选择性,已被用于氧化反应、氢化反应、烯丙基取代反应、羰基化反应、Suzuki和Heck偶联反应、烯烃的不对称二羟基化反应及有机醛、酮的合成反应体系中。本文对其制备方法、可能结构及其在各种反应体系中的催化性能进行了综述。     

Flow fine synthesis with heterogeneous catalysts

In the past few decades, organic reactions under flow conditions have attracted increasing attention. Flow reactions have a number of advantages over batch reactions in terms of environmental compatibility, efficiency, and safety. In particular, flow reactions with heterogeneous catalysts that yield desired products without significant levels of by-product formation can enable purification processes to be avoided. This feature can allow flow reactions to be assembled in a multi-step and continuous manner for the synthesis of complex molecules. These new techniques have opened up new approaches to the synthesis of fine chemicals and are expected to play a prominent role in future chemical manufacturing processes. In this context, this review aims to summarize recent developments in continuous-flow reactions with heterogeneous catalysts for synthesis of fine chemicals.     

Non‐Redox‐Metal‐Catalyzed Redox Reactions: Zinc Catalysts

The advantages of zinc catalysts, such as their low toxicity, low cost, and environmentally benignity, are encouraging organic chemists to explore their applications in organic synthesis. As a non‐redox metal, zinc catalysts have been investigated in redox reactions over the past few decades. Because of the importance of redox reactions, the interest in zinc catalysts, and the fact that no review on zinc‐catalyzed redox reactions has been published, herein, I have collected and summarized the main contributions in this area. This review is divided into two parts: reduction reactions and oxidation reactions.     

Application of silver-promoted reactions in the synthesis of five-membered O-heterocycles

The investigation of facial protocols for chemical synthesis is a growing area of interest due to increasing environmental issues. The use of catalysts in organic reactions has gained extensive interest. Metal and nonmetal catalysts provided a new improved alternative to traditional methods in modern synthetic chemistry. The aim of the present review is to focus on the applications of silver-promoted reactions for the synthesis of oxygen containing five-membered heterocycles which have significance in organic synthesis, pharmaceuticals, agrochemicals, and among others.     

Recent Advances in Multifunctional Capsule Catalysts in Heterogeneous Catalysis?

Capsule catalysts composed of pre-shaped core catalysts and layer zeolites have been widely used in the tandem reactions where multiple continuous reactions are combined into one process. They show excellent catalytic performance in heterogeneous catalysis, including the direct synthesis of middle isoparaffins or dimethyl ether from syngas, as compared to the conventional hybrid catalysts. The present review highlights the recent development in the design of capsule catalysts and their catalytic applications in heterogeneous catalysis. The capsule catalyst preparation methods are introduced in detail, such as hydrothermal synthesis method, dual-layer method, physically adhesive method and single crystal crystallization method. Furthermore, several new applications of capsule catalysts in heterogeneous catalytic processes are presented such as in the direct synthesis of liquefied petroleum gas from syngas, the direct synthesis of para-xylene from syngas and methane dehydroaromatization. In addition, the development in the design of multifunctional capsule catalysts is discussed, which makes the capsule catalyst not just a simple combination of two different catalysts, but has some special functions such as changing the surface hydrophobic or acid properties of the core catalysts. Finally, the future perspectives of the design and applications of capsule catalysts in heterogeneous catalysis are provided.     

Recent Advances in Asymmetric Catalysis Using p-Block Elements

The development of new methods for enantioselective reactions that generate stereogenic centres within molecules are a cornerstone of organic synthesis. Typically, metal catalysts bearing chiral ligands as well as chiral organocatalysts have been employed for the enantioselective synthesis of organic compounds. In this review, we highlight the recent advances in main group catalysis for enantioselective reactions using the p-block elements (boron, aluminium, phosphorus, bismuth) as a complementary and sustainable approach to generate chiral molecules. Several of these catalysts benefit in terms of high abundance, low toxicity, high selectivity, and excellent reactivity. This minireview summarises the utilisation of chiral p-block element catalysts for asymmetric reactions to generate value-added compounds.     

Amidines, isothioureas, and guanidines as nucleophilic catalysts

Over the last ten years there has been a huge increase in development and applications of organocatalysis in which the catalyst acts as a nucleophile. Amidines and guanidines are often only thought of as strong organic bases however, a number of small molecules containing basic functional groups have been shown to act as efficient nucleophilic catalysts. This tutorial review highlights the use of amidine, guanidine, and related isothiourea catalysts in organic synthesis, as well as the evidence for the nucleophilic nature of these catalysts. The most common application of these catalysts to date has been in acyl transfer reactions, although the application of these catalysts towards other reactions is an increasing area of interest. In this respect, amidine and guanidine derived catalysts have been shown to be effective in catalysing aldol reactions, Morita-Baylis-Hillman reactions, conjugate additions, carbonylations, methylations, silylations, and brominations.     

聚合物负载的手性催化剂和手性试剂和合成及应用

近年来,用聚合物负载的手性催化剂和手性试剂完成的不对称合成反应主要集中在潜手性酮的不对称还原反应;烯烃的不对称双羟基化反应;烯烃的不对称环氧化反应;不对称Ｄｉｅｌｓ－Ａｌｄｅｒ反应和饱和碳原子上的不对称取代反应。就近十年来聚合物负载手性催化剂和手性试剂的合成及应用进行了讨论。     

DNA‐Based Hybrid Catalysts for Asymmetric Organic Synthesis

Stereoselective hybrid systems based on metal‐assisted catalysis with a chiral biomacromolecule form an attractive research area for the synthesis of enantiomerically pure compounds. Although various methods are available for this purpose, most rely on the use of enzymes, proteins, or RNA. The application of DNA‐based hybrid catalysts for enantioselective synthesis emerged only a few years ago. DNA‐based hybrid catalysts have been self‐assembled from DNA and a metal complex with a specific ligand through supramolecular or covalent anchoring strategies and have demonstrated high stereoselectivity and rate enhancement in Lewis acid catalyzed reactions, such as Diels–Alder, Michael addition, and Friedel–Crafts reactions. For these reactions, cheap and commercially available salmon testes DNA has generally been used. In this Minireview, we summarize recent developments in the area of asymmetric catalysis with DNA‐based hybrid catalysts.     

Use of 2,4,6-trichloro-1,3,5-triazine (TCT) as organic catalyst in organic synthesis

Organic catalysts have found wide applications in organic synthesis. Many organic reactions, which originally do not occur under normal conditions or are difficult to operate normally, have been successfully conducted under mild conditions in the presence of catalysts. In recent years, 2,4,6-trichloro-1,3,5-triazine (TCT, cyanuric chloride) has been used as organic catalyst in many organic synthesis, because it is stable, nonvolatile, inexpensive, commercially available, and easy to handle. On account of these properties it has been used as a green catalyst and sometimes is a catalyst of choice in organic reactions.     

金属-有机骨架衍生催化剂在二氧化碳加氢和费托合成反应中的应用

CO₂加氢和费托合成反应是C1化学中重要的研究领域,CO₂加氢制备高附加值化学品和燃料有助于降低大气中CO₂浓度,减轻化石燃料消耗的压力;费托合成反应是以非石油资源为原料生产液体燃料和化学品的重要路径。 开发新型、高效、稳定的催化剂是CO₂加氢和费托合成反应的关键点之一。 利用金属-有机骨架(Metal-Organic Frameworks,MOFs)材料的特点制备的MOFs衍生催化剂在CO₂加氢和费托合成反应中具有较好的应用前景。 本文综述了CO₂加氢和费托合成反应中MOFs衍生催化剂的制备方法,以及催化剂在各反应中的催化性能,并对目前所存在的问题以及今后的发展进行了总结和展望。     

磁性纳米粒子负载钯催化剂在C-C键偶联反应中的应用

磁性纳米粒子(MNPs)负载钯催化剂因具有高的催化活性及易于原位磁分离回收等优点而得到快速发展,成为一类具有广泛应用前景的纳米催化剂,在学术及工业领域均受到广泛的关注。 本文对近年来MNPs负载钯催化剂在Suzuki、Heck等C-C偶联反应中的应用研究进行简要阐述,并对其发展前景进行了展望。     

环钯化合物在Heck反应中的应用研究

钯催化交叉偶联反应在化学工业、合成天然产物及生物活性物质中有着广泛的应用.催化剂体系是交叉偶联反应研究的核心.环钯化合物结构简单、性能稳定,在催化交叉偶联反应中具有高活性、高选择性,引起研究者们的极大关注,不断有新的环钯化合物被合成出来,其催化性能也得到了研究.本文综述了环钯化合物的合成方法及其在Heck反应中的应用.     

One-component bimetallic aluminium(salen)-based catalysts for cyclic carbonate synthesis and their immobilization

The development of one-component, bimetallic μ-oxoaluminium(salen) complexes as highly active catalysts for the synthesis of cyclic carbonates from terminal epoxides is described. The resulting homogeneous catalysts are used in batch reactions at room temperature and one atmosphere pressure. The catalysts have also been immobilized onto various support materials and used in either batch reactions or gas-phase flow reactions with ethylene and propylene oxides. Catalyst lifetime, deactivation and reactivation have been studied in both batch and flow reactions, and it has been shown that of the impurities present in power station flue gas, only sulfur trioxide deactivates the catalyst and at the concentrations of sulfur trioxide present in flue gas, this deactivation would require more than one years exposure of the catalyst to flue gas.     

Synthetic routes to seven and higher membered S-heterocycles by use of metal and nonmetal catalyzed reactions

Nitrogen, oxygen, and sulfur containing heterocycles have a wide range of biological activities. Metal and nonmetal catalysts are used in organic reactions with high activity. New strategies have been developed for the preparation of heterocycles in the last decades. The metal and nonmetal catalyzed synthesis of heterocycles is becoming an important and highly rewarding protocol in organic synthesis. In this review article, the synthesis of seven and higher-membered S-heterocycles is presented with the application of metal and nonmetal catalysts for the period from 1968 to 2018.     

贵金属钌基催化剂合成及应用研究进展

钌催化剂是近年来新兴的贵金属催化剂,其负载型催化剂具有节约成本、可回收利用、催化性能优异等优势,受到研究人员的广泛关注.本文对负载型钌基催化剂在氨合成反应、加氢反应、氧化反应的合成及应用进行了综述,主要阐述了反应过程中的载体与助剂、制备方法和催化性能,并对当前反应中存在的问题进行归纳和总结,最后提出负载型钌基催化剂现阶...     

Synthesis of seven and higher-membered heterocycles using ruthenium catalysts

A wide variety of biological activities are possessed by nitrogen, oxygen, and sulfur containing heterocycles and many methods are explored for the preparation of these heterocyclic compounds. Metal catalysts are used in organic reactions with high activity. The synthesis of heterocycles with the help of metal catalysts became very important in organic synthesis. New protocols have been investigated for the synthesis of heterocycles in the last decades. In present review article I have concentrated on the synthesis of seven and higher-membered heterocylces in the presence of ruthenium catalyst.     

Carbohydrate based chiral iodoarene catalysts for enantioselective dearomative spirocyclization

Organocatalysis using chiral iodoarenes enables many different enantioselective chemical reactions with cheap, easily accessible and robust catalysts. Carbohydrates have often been used as starting materials for the synthesis of chiral ligands for transition metal catalysts. Here, we now present the synthesis of the first carbohydrate based iodoarene catalysts which can be synthesized in one step starting from known compounds. These catalysts were used for oxidative spriolactonization of 3-(1-hydroxynaphthalen-2-yl)propanoic acid to afford the corresponding spirolactone in yields up to 77% and enantiomeric ratios er up to 80:20.     

Efficient Tandem Synthesis of Methyl Esters and Imines by Using Versatile Hydrotalcite‐Supported Gold Nanoparticles

Efficient basic hydrotalcite (HT)‐supported gold nanoparticle (AuNP) catalysts have been developed for the aerobic oxidative tandem synthesis of methyl esters and imines from primary alcohols catalyzed under mild and soluble‐base‐free conditions. The catalytic performance can be fine‐tuned for these cascade reactions by simple adjustment of the Mg/Al atomic ratio of the HT support. The one‐pot synthesis of methyl esters benefits from high basicity (Mg/Al=5), whereas moderate basicity greatly improves imine selectivity (Mg/Al=2). These catalysts outperform previously reported AuNP catalysts by far. Kinetic studies show a cooperative enhancement between AuNP and the surface basic sites, which not only benefits the oxidation of the starting alcohol but also the subsequent steps of the tandem reactions. To the best of our knowledge, this is the first time that straightforward control of the composition of the support has been shown to yield optimum AuNP catalysts for different tandem reactions.     

Recent advances in asymmetric reactions catalyzed by chiral phosphoric acids

The very recent advances in chiral phosphoric acids (CPAs) catalyzed asymmetric reactions are discussed.