Topics in Current Chemistry最新文献

This review systematically analyzes recent advances in transition metal-catalyzed carbene and nitrene insertion into unactivated aliphatic C(sp³)–H bonds through inner-sphere mechanisms, offering a critical synthesis of mechanistic insights and synthetic applications from 2016 to 2024. By contrasting inner- and outer-sphere pathways, we elucidate how metal–substrate coordination governs regioselectivity, catalyst design, and substrate compatibility. Key discussions focus on breakthroughs in Rh(III), Pd(II), Co(III), Ir(III), and Ni(II) catalytic systems, emphasizing their distinct electronic and steric control strategies for directing C–H activation and migratory insertion. Notable achievements include the functionalization of sterically hindered substrates, enantioselective aminations via chiral ligand engineering, and cascade transformations enabled by metal-mediated β-elimination. We highlight emerging trends in sustainable catalysis using earth-abundant metals (e.g., Co, Ni), while addressing persistent challenges such as directing group dependency, catalyst deactivation, and limited substrate scope. The review further proposes strategic frameworks for future innovation, including (1) computational ligand optimization to enhance regiochemical control, (2) transient directing group strategies for native functional group tolerance, and (3) bifunctional catalyst design to differentiate electronically equivalent C–H bonds. By bridging mechanistic understanding with practical synthetic goals, this work establishes a roadmap for advancing precision C(sp³)–H functionalization in complex molecule synthesis and industrial applications.

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Spiroethers, a subset of natural and synthetic spirocycles, possess various biological activities. These motifs are found in natural products and exhibit anticancer, antidepressant, antiviral, antimalarial, and antituberculosis properties. Because of their exceptional structures, spiroethers can serve as important bioactive scaffolds in the pharmaceutical industry to improve bioavailability and stability and in drug discovery. Many of these compounds can also be used in perfumes and flavors owing to their olfactory properties. Given the increasing interest in spiroether-derived compounds in the pharmaceutical industry and the low yields of spiroethers provided by natural sources, which are not economically viable for industrial demand, synthetic approaches have garnered significant attention. In this review, we provide insight into 16 different approaches suggested for the synthesis of spiroethers; these methods are classified in the following five categories: catalytic methods (four methods), cyclization reactions (three methods), nucleophilic/electrophilic additions (two methods), functional group transformation (three methods), and miscellaneous (four methods). Certain advantages including material availability, high yield, simple procedures, low cost, ability to enhance biological properties of the final products, and so on are reported for these approaches.

Dipyrroethanes/dipyrroethenes (DPEs) containing two pyrroles connected by two meso sp³/sp² carbons are very useful precursors for the synthesis of very novel porphyrinoids. Dipyrromethanes/dipyrromethenes (DPMs) that consist of two pyrrole rings connected via one meso sp³/sp² carbon are the most popular precursors for the synthesis of several types of porphyrinoids. Dipyrromethanes/dipyrromethenes can be readily prepared by condensing aldehyde and pyrrole under acid-catalyzed conditions, whereas dipyrroethenes (DPEs) require a few skilled synthetic steps to be obtained in good quantities. Especially, dipyrroethenes exist in E/Z-isomeric mixtures but their separation is not required for the synthesis of porphyrinoids. In the last decade, DPEs have been used as key precursors to synthesize contracted porphyrins such as triphyrins(2.1.1), porphyrin isomers such as porphycene(2.0.2.0), and several expanded porphyrins. This review describes different methods available for the synthesis of 5,6-di(alkyl/aryl/heteroaryl) dipyrroethanes/dipyrroethenes and their use in the synthesis of different porphyrinoids ranging from contracted porphyrinoids to expanded porphyrinoids. The structure, reactivity, and physico-chemical properties of various porphyrinoids which were synthesized from DPEs are also discussed.

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Non-coding RNAs (ncRNAs) are functional RNA molecules that do not code for proteins. Among these, circular RNAs (circRNAs) represent a recently identified class of endogenous ncRNAs with a pivotal role in gene regulation, alongside short ncRNAs (e.g., microRNAs or miRNAs) and long non-coding RNAs (lncRNAs). CircRNAs are characterized by their single-stranded, covalently closed circular structure, which lacks polyadenylated tails and 5'-3' ends. This unique circular conformation makes them resistant to exonuclease degradation, rendering them more stable than linear RNAs, such as mRNAs in human blood cells, which highlights their potential as biomarkers. Both linear and circular RNAs are derived from pre-mRNA precursors. However, while linear RNAs are produced through conventional splicing, circRNAs are primarily formed through a process known as reverse splicing. CircRNAs can be categorized into five basic types: exon circRNAs, circular intronic RNAs, exon–intron circRNAs, intergenic circRNAs, and fusion circRNAs. These molecules have been shown to significantly influence key hallmarks of cancer, including sustained growth signaling, proliferation, angiogenesis, resistance to apoptosis, unlimited replicative potential, and metastasis. This article will delve into the biogenesis and functions of circRNAs, explore their roles in cancer, and discuss their potential applications as therapeutic options and diagnostic biomarkers.

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The Horner-Wadsworth-Emmons (HWE) reaction is a commonly used and reliable phenomenon for carbon–carbon olefination in organic chemistry, carried out by treating aldehyde or ketones with phosphonate esters to afford the substituted alkenes. HWE reaction has also been observed to be involved in the stereo-controlled syntheses of naturally occurring compounds that acquire pharmaceutical profiles against various diseases. In this article, recent implementations of Horner-Wadsworth-Emmons reaction towards the notable total syntheses of naturally occurring compounds such as polyketides have been summarized.

Cinchona alkaloids are naturally occurring chiral molecules that have emerged as catalysts in asymmetric organocatalysis especially in enantioselective transformations because of their inherent chirality and unique structural features. Immobilizing these alkaloids on polymeric supports has significantly influenced their use in catalysis. Polymer-anchored cinchona alkaloids combine the catalytic efficacy of cinchona derivatives with additional benefits of polymer chain, such as ease of recovery, recyclability, reusability, and reduced environmental impact. These polymer-supported cinchona alkaloids have found wide applications in enantioselective reactions such as Michael addition, aldol condensations, Henry reaction, dimerization reaction, dihydroxylation, and benzylation. Various strategies have been employed for anchoring cinchona alkaloids onto polymers, including covalent attachment of alkaloids in the polymer side chain or main chain, and ionic attachment of alkaloids via quaternization in the main chain or side chain of polymer. This review focuses on the various synthetic methodologies for the preparation of polymer-anchored cinchona alkaloids and their application in numerous asymmetric transformations.

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Acyl and aroyl hydrazones are hydrazine derivatives with unique structural variations and multiple applications in various disciplines, including medicinal chemistry, materials, and agrochemicals research. The presence of numerous reactive sites in acyl hydrazones established it as a privileged structure class in organic chemistry and, hence, serve as an important intermediate in the synthesis of pharmaceutically significant compounds. The intrinsic nature of the acylhydrazone group leads to various dynamic processes, including conformational, configurational, and tautomeric interconversions. Their dynamic behavior in organic frameworks is mainly attributed to hindered rotation around the imine C=N bond and –CONH– amide bond. It is crucial to comprehend the geometrical and conformational behavior of hydrazone derivatives in order to understand their structural attributes, reactivity, and interactions with other molecules. This review article provides an in-depth and up-to-date examination of the geometrical and conformational properties of acyl and aroyl hydrazones showcasing chronological progression of advancements in N-acyl/aroyl hydrazones (NAHs) over time spanning from 1955 to 2025. The insights gained from this analysis will be a helpful resource for researchers and chemists working on designing and developing new compounds with improved characteristics for various applications in chemistry and medicine.

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The increasing use of pesticides necessitates the development of innovative analytical methods to regulate environmental impacts and ensure food safety. Aptamer-based sensors hold great promise for pesticide detection owing to their superior selectivity, stability, repeatability, and regenerative capabilities. Integrated with nanomaterials, aptasensors have demonstrated enhanced sensitivity for detecting a broad range of pesticides. This study first introduces the aptamer binding mechanism and presents the fundamental concept and justification for selecting aptamer over other biorecognition molecules. It then provides a comprehensive review of recent advancements and applications of various types of aptasensors for targeted pesticide detection, including electrochemical, fluorescent, colorimetric, electrochemiluminescent, and surface-enhanced Raman scattering (SERS) aptasensors. Additionally, it offers a comparative analysis of different aptasensors by evaluating their strengths and limitations. Finally, this review discusses strategies, such as advanced Systemic Evolution of Ligands by Exponential Enrichment (SELEX) technique, self-assembled monolayers (SAMs), and the use of antifouling agents to improve the aptamer’s selectivity, signal-to-noise ratio, and mitigate nonspecific adsorption challenges. These developments are essential for creating highly sensitive and selective aptasensors, facilitating their practical use in environmental monitoring and food safety.

Bridged heterocycles are highly relevant in medicinal chemistry and drug discovery due to the unique features associated with their three-dimensional configuration that ensures great scaffold complexity. In general, inserting bridged systems into a chemical structure positively influences the pharmacokinetic (PK) profile of leads, reducing lipophilicity and enhancing metabolic stability. Several optimization studies show that bridged systems often promoted a significant improvement of the small molecule–enzyme binding interaction due to conformational changes within the biological target active site. To date, many drugs including bridged cores are available in the market to cure several diseases. Given the broad range of biological activities of naturally occurring and (semi)-synthetic bridgehead heterocycles, here, we have thoroughly reviewed the rational design and the structure–activity relationship (SAR) studies of the most remarkable bridged compounds developed during the past decade, to highlight both the chemical and biological roles of these motifs.

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This review discusses recent progress in the most significant synthetic approaches involving transformations under the Mitsunobu reaction. The Mitsunobu reaction entails the "redox" condensation of an acidic pronucleophile ‘Nu-H’ and an electrophilic primary or secondary alcohol, facilitated by stoichiometric amounts of phosphines and azodicarboxylate reagents. Widely utilized for dehydrative oxidation–reduction condensation, this reaction shows synthetic utility through its tolerance of a broad range of acidic pronucleophiles, including carboxylic acids, pro-imides, hydroxamates, phenols, thiols, fluorinated alcohols, oximes, thioamides, pyridinium and imidazolium salts, pyrimidine bases, α-ketoesters, and trimethylmethane tricarboxylate, thereby yielding a variety of functional and potentially biologically active compounds. The purpose of this review is to focus on recent advances and applications of Mitsunobu reaction chemistry, particularly from 2010 to 2024. In addition to discussing newer reagents that facilitate purification, we will describe contemporary applications of this chemistry, especially concerning the synthesis of potential biological compounds and their precursors. This focus review of the Mitsunobu reaction summarizes its origins, the current understanding of its mechanism, and recent improvements and applications. We aim for this work to serve as a useful resource for scientists working in this research domain.