Topics in Current Chemistry最新文献

Nitrogen heterocycles are part of the structure of natural products and agents with important biological activity, such as antiviral, antibiotic, and antitumor drugs. For this reason, heterocyclic compounds are one of today’s most desirable synthetic targets and the Povarov reaction is a powerful synthetic tool for the construction of highly functionalized heterocyclic systems. This process involves an aromatic amine, a carbonyl compound, and an olefin or acetylene to give rise to the formation of a nitrogen-containing heterocycle. This review illustrates advances in the synthetic aspects of the intramolecular Povarov reaction for the construction of intricate nitrogen-containing polyheterocyclic compounds. This original review presents research done in this field, with references to important works by internationally relevant research groups on this current topic, covering the literature from 1992 to 2022. The intramolecular Povarov reactions are described here according to the key processes involved, using different combinations of aromatic or heteroaromatic amines, and aliphatic, aromatic, or heteroaromatic aldehydes. Some catalytic reactions promoted by transition metals are detailed, as well as the oxidative Povarov reaction and some asymmetric intramolecular Povarov processes.

In recent years, the combination of both thermal and photochemical contributions has provided interesting opportunities for solar upgrading of catalytic processes. Photothermal catalysis works at the interface between purely photochemical processes, which involve the direct conversion of photon energy into chemical energy, and classical thermal catalysis, in which the catalyst is activated by temperature. Thus, photothermal catalysis acts in two different ways on the energy path of the reaction. This combined catalysis, of which the fundamental principles will be reviewed here, is particularly promising for the activation of small reactive molecules at moderate temperatures compared to thermal catalysis and with higher reaction rates than those attained in photocatalysis, and it has gained a great deal of attention in the last years. Among the different applications of photothermal catalysis, CO₂ conversion is probably the most studied, although reaction mechanisms and photonic-thermal synergy pathways are still quite unclear and, from the reaction route point of view, it can be said that photothermal-catalytic CO₂ reduction processes are still in their infancy. This article intends to provide an overview of the principles underpinning photothermal catalysis and its application to the conversion of CO₂ into useful molecules, with application essentially as fuels but also as chemical building blocks. The most relevant specific cases published to date will be also reviewed from the viewpoint of selectivity towards the most frequent target products.

Synthesis of pyrazole-fused heterocycles has gained considerable attention in recent years due to their wide applications in medicinal chemistry. Aminopyrazoles are versatile building blocks for the synthesis of pyrazole-fused heterocycles by multicomponent reactions. Due to the presence of multiple reaction sites, they have fascinating chemical reactivity. Thus, they have been extensively used in multicomponent reactions for the construction of pyrazole-fused heterocycles. Although few review articles on the preparation and applications of aminopyrazoles are known in the literature, to date there is no dedicated review article on the construction of pyrazole-fused heterocycles exploring the reactivity of amino pyrazoles as C,N-binucleophiles in multicomponent reactions. Considering this, herein the multicomponent reactions for the construction of pyrazole-fused heterocycles exploring C,N-binucleophilic nature of amino pyrazoles have been reported.

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Patterning is crucial for the large-scale application of functional materials. Laser-induced transfer is an emerging patterning method for additively depositing functional materials to the target acceptor. With the rapid development of laser technologies, this laser printing method emerges as a versatile method to deposit functional materials in either liquid or solid format. The emerging applications such as solar interfacial evaporation, solar cells, light-emitting diodes, sensors, high-output synthesis, and other fields are rising fields benefiting from laser-induced transfer. Following a brief introduction to the principles of laser-induced transfer, this review will comprehensively deliberate this novel additive manufacturing method, including preparing the donor layer and the applications, advantages, and limitations of this technique. Finally, perspectives for handling current and future functional materials using laser-induced transfer will also be discussed. Non-experts in laser technologies can also gain insights into this prevailing laser-induced transfer process, which may inspire their future research.

Oxime esters as the applicable building blocks, internal oxidizing agents, and directing groups in the synthesis of –, S-, and O-containing heterocycle scaffolds have gained great attention in the last decade. This review provides an overview of recent advances in the cyclization of oxime esters with various functional group reagents under transition metal and transition metal-free catalyzed conditions. Moreover, the mechanistic aspects of these protocols are explained in detail.

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Acetylcholine (ACh) is one of the most crucial neurotransmitters of the cholinergic system found in vertebrates and invertebrates and is responsible for many processes in living organisms. Disturbances in ACh transmission are closely related to dementia in Alzheimer’s and Parkinson’s disease. ACh in biological samples is most often determined using chromatographic techniques, radioenzymatic assays, enzyme-linked immunosorbent assay (ELISA), or potentiometric methods. An alternative way to detect and determine acetylcholine is applying spectroscopic techniques, due to low limits of detection and quantification, which is not possible with the methods mentioned above. In this review article, we described a detailed overview of different spectroscopic methods used to determine ACh with a collection of validation parameters as a perspective tool for routine analysis, especially in basic research on animal models on central nervous system. In addition, there is a discussion of examples of other biological materials from clinical and preclinical studies to give the whole spectrum of spectroscopic methods application. Descriptions of the developed chemical sensors, as well as the use of flow technology, were also presented. It is worth emphasizing the inclusion in the article of multi-component analysis referring to other neurotransmitters, as well as the description of the tested biological samples and extraction procedures. The motivation to use spectroscopic techniques to conduct this type of analysis and future perspectives in this field are briefly discussed.

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Hydrogen peroxide is a powerful and green oxidant that allows for the oxidation of a wide span of organic and inorganic substrates in liquid media under mild reaction conditions, and forms only molecular water and oxygen as end products. Hydrogen peroxide is therefore used in a wide range of applications, for which the well-documented and established anthraquinone autoxidation process is by far the dominating production method at the industrial scale. As this method is highly energy consuming and environmentally costly, the search for more sustainable synthesis methods is of high interest. To this end, the article reviews the basis and the recent development of the photocatalytic synthesis of hydrogen peroxide. Different oxygen reduction and water oxidation mechanisms are discussed, as well as several kinetic models, and the influence of the main key reaction parameters is itemized. A large range of photocatalytic materials is reviewed, with emphasis on titania-based photocatalysts and on high-prospect graphitic carbon nitride-based systems that take advantage of advanced bulk and surface synthetic approaches. Strategies for enhancing the performances of solar-driven photocatalysts are reported, and the search for new, alternative, photocatalytic materials is detailed. Finally, the promise of in situ photocatalytic synthesis of hydrogen peroxide for water treatment and organic synthesis is described, as well as its coupling with enzymes and the direct in situ synthesis of other technical peroxides.

α-C–H functionalization of tertiary amines has been a highly studied field for the past two decades because several important nitrogen containing heterocycles or compounds can be synthesized through this strategy. Though transition metal catalysts and some metal-free catalysts are mainly used for these reactions, a few catalyst-free reactions have recently been efficiently performed. Catalyst-free reactions are cost-effective, less sensitive to air/moisture, easier to operate, have a simple purification process, and are relatively environment-friendly. In this article, we have summarized all the α-C–H functionalization reactions of tertiary amines performed without using any external catalysts. The content of this article will undoubtedly encourage readers to do more work in this area.

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Solid-state nanopores/nanochannels, with their high stability, tunable geometry, and controllable surface chemistry, have recently become an important tool for constructing biosensors. Compared with traditional biosensors, biosensors constructed with solid-state nanopores/nanochannels exhibit significant advantages of high sensitivity, high specificity, and high spatiotemporal resolution in the detection single entities (such as single molecules, single particles, and single cells) due to their unique nanoconfined space-induced target enrichment effect. Generally, the solid-state nanopore/nanochannel modification method is the inner wall modification, and the detection principles are the resistive pulse method and the steady-state ion current method. During the detection process, solid-state nanopore/nanochannel is easily blocked by single entities, and interfering substances easily enter the solid-state nanopore/nanochannel to generate interference signals, resulting in inaccurate measurement results. In addition, the problem of low flux in the detection process of solid-state nanopore/nanochannel, these defects limit the application of solid-state nanopore/nanochannel. In this review, we introduce the preparation and functionalization of solid-state nanopore/nanochannel, the research progress in the field of single entities sensing, and the novel sensing strategies on solving the above problems in solid-state nanopore/nanochannel single-entity sensing. At the same time, the challenges and prospects of solid-state nanopore/nanochannel for single-entity electrochemical sensing are also discussed.

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