Studies on the biological activity of gem-difluorinated 3,3′-spirocyclic indole derivatives

Diastereoselective radical cascade cyclization to access indole-fused diazepine derivatives

The synthesis of polycyclic indoles is significant in organic chemistry, due to such heterocyclic frameworks being present in numerous bioactive pharmaceuticals and natural alkaloids. Herein, we provide an efficient radical cascade cyclization strategy to generate indole-fused diazepine derivatives using phosphoryl or sulfonyl radicals with N-(2-(1H-indol-1-yl)phenyl)-N-methylmethacrylamides. The merits of this synthesis are attributed to its accessible starting materials, broad substrate compatibility and excellent diastereoselectivity.

Design, synthesis and antiviral activity of indole derivatives containing quinoline moiety

A series of indole derivatives containing quinoline structures were designed and synthesized. The synthesized compounds were characterized by NMR and HRMS. And W14 was performed by single crystal X-ray diffraction experiments. The antiviral activity studies showed that some of the target compounds possessed significant activity against tobacco mosaic virus (TMV). In particular, W20 had significant activity. The results of in vivo anti-TMV activity assay showed that W20 possessed the best curative and protective activities with EC50 values of 84.4 and 65.7 μg/mL, which were better than ningnanmycin (NNM) 205.1 and 162.0 μg/mL, respectively. The results of Microscale thermophoresis (MST) showed that W20 had a strong binding affinity for the tobacco mosaic virus coat protein (TMV-CP) with a dissociation constant (Kd) of 0.00519 μmol/L, which was superior to that of NNM (1. 65320 μmol/L). The molecular docking studies were in accordance with the experimental results. In addition, the determination of malondialdehyde (MDA) content in tobacco leaves showed that W20 improved the disease resistance of tobacco. Overall, this study shows that indole derivatives containing quinoline can be used as new antiviral agents for plant viruses for further research.

Application of Difluoromethyl Isosteres in the Design of Pesticide Active Molecules

Difluoromethyl (CF2H) groups have been found in many listed pesticides due to their unique physical and chemical properties and outstanding biological activity. In pesticide molecules, compared with the drastic changes brought by trifluoromethyl, difluoromethyl usually moderately regulates the metabolic stability, lipophilicity, bioavailability, and binding affinity of compounds. Therefore, difluoromethylation has become an effective means to modify the biological activity of pesticide molecules. This paper reviews the representative literatures and patents containing difluoromethyl groups in the past 10 years, and introduces the research progress. The aim is to provide an effective reference value for the study of difluoromethyl in pesticides.

Expeditious Synthesis of Spiroindoline Derivatives via Tandem C(sp2)-H and C(sp3)-H Bond Functionalization of N-Methyl-N-nitrosoanilines

Presented herein is a novel synthesis of pharmaceutically privileged spiroindoline derivatives via cascade reactions of N-methyl-N-nitrosoanilines with diazo homophthalimides. A group of mechanistic studies disclosed that the formation of product involves an unusual reaction mode of N-methyl-N-nitrosoaniline featuring an initial C(sp2)-H bond activation/alkylation followed by a C(sp3)-H bond activation/spiroannulation. To our knowledge, this is the first example in which N-methyl-N-nitrosoaniline acts as a C3N1 synthon to accomplish formal [4+1] spiroannulation with the participation of the N-methyl unit rather than the previously reported C2N1 synthon to undergo formal [3+2] annulation without the participation of the N-methyl unit. In general, this newly developed synthetic protocol features simple and readily accessible starting materials, valuable products, unique reaction mechanism, high efficiency and atom-economy, excellent compatibility with diverse functional groups, and ready scalability.

Design, Synthesis, Antifungal Evaluation, Structure-Activity Relationship (SAR) Study, and Molecular Docking of Novel Spirotryprostatin A Derivatives

Phytopathogenic fungi cause plant diseases and economic losses in agriculture. To efficiently control plant pathogen infections, a total of 19 spirotryprostatin A derivatives and 26 spirooxindole derivatives were designed, synthesized, and tested for their antifungal activity against ten plant pathogens. Additionally, the intermediates of spirooxindole derivatives were investigated, including proposing a mechanism for diastereoselectivity and performing amplification experiments. The bioassay results demonstrated that spirotryprostatin A derivatives possess good and broad-spectrum antifungal activities. Compound 4d exhibited excellent antifungal activity in vitro, equal to or higher than the positive control ketoconazole, against Helminthosporium maydis, Trichothecium roseum, Botrytis cinerea, Colletotrichum gloeosporioides, Fusarium graminearum, Alternaria brassicae, Alternaria alternate, and Fusarium solan (MICs: 8-32 µg/mL). Compound 4k also displayed remarkable antifungal activity against eight other phytopathogenic fungi, including Fusarium oxysporium f. sp. niveum and Mycosphaerella melonis (MICs: 8-32 µg/mL). The preliminary structure-activity relationships (SARs) were further discussed. Moreover, molecular docking studies revealed that spirotryprostatin A derivatives anchored in the binding site of succinate dehydrogenase (SDH). Therefore, these compounds showed potential as natural compound-based chiral fungicides and hold promise as candidates for further enhancements in terms of structure and properties.

Et2Zn-Mediated Radical (3 + 2) Cycloaddition of Vinyl Azides with Ethyl Iododifluoroacetate to Access 3,3-Difluoro-γ-lactams

A diethylzinc-mediated radical (3 + 2) cycloaddition of vinyl azides with ethyl iododifluoroacetate is presented. The developed reaction features good functional group tolerance, broad substrate scope, and operational simplicity, enabling efficient assembly of a wide range of 3,3-difluoro-γ-lactam derivatives bearing an O-substituted quaternary carbon center in moderate to good yields. The utility of the method is showcased by a scaled-up reaction, conversion of the product, and late-stage structural modifications of a variety of pharmaceutical compounds.

Base-Promoted Formal (3 + 2) Cycloaddition of α-Halohydroxamates with Electron-Deficient Alkenyl-iminoindolines To Synthesize Spiro-indolinepyrrolidinones

Construction of pyrrolidinyl-spiroindoles with easily available starting materials has attracted considerable attention from the synthesis community and is in great demand. Here, we describe a base-promoted formal (3 + 2) cycloaddition of α-halohydroxamates with alkenyl-iminoindolines. The present methodology features mild reaction conditions and a broad substrate scope with up to 99% yield and excellent diastereoselectivity. The versatility of this approach is demonstrated through valuable synthetic transformations. Preliminary mechanistic studies shed light on the mechanism of this cycloaddition process.

Synthesis of (E)-2-(1-(methoxyimino)ethyl)-2-phenylbenzofuran-3(2H)-ones from (E)-1-(benzofuran-2-yl)ethan-1-one O-methyl oximes and iodobenzenes via a palladium-catalyzed dearomative arylation/oxidation reaction

A new method has been successfully developed that offers a facile and reliable approach for synthesizing (E)-2-(1-(methoxyimino)ethyl)-2-phenylbenzofuran-3(2H)-one, providing 28 compounds. This optimized process enables efficient preparation of a wide range of compounds using readily available (E)-1-(benzofuran-2-yl)ethan-1-one O-methyl oxime and iodobenzene, and provides alternative ideas for the structural modification of benzofuran ketones.

Recent Achievements in Antiviral Agent Development for Plant Protection

Plant virus disease is the second most prevalent plant diseases and can cause extensive loss in global agricultural economy. Extensive work has been carried out on the development of novel antiplant virus agents for preventing and treating plant virus diseases. In this review, we summarize the achievements of the research and development of new antiviral agents in the recent five years and provide our own perspective on the future development in this highly active research field.

Spiro Derivatives in the Discovery of New Pesticides: A Research Review

Spiro compounds are biologically active organic compounds with unique structures, found in a wide variety of natural products and drugs. They do not readily lead to drug resistance due to their unique mechanisms of action and have, therefore, attracted considerable attention regarding pesticide development. Analyzing structure-activity relationships (SARs) and summarizing the characteristics of spiro compounds with high activity are crucial steps in the design and development of new pesticides. This review mainly summarizes spiro compounds with insecticidal, bactericidal, fungicidal, herbicidal, antiviral, and plant growth regulating functions to provide insight for the creation of new spiro compound pesticides.

Recent Research Progress: Discovery of Anti-Plant Virus Agents Based on Natural Scaffold

Plant virus diseases, also known as “plant cancers”, cause serious harm to the agriculture of the world and huge economic losses every year. Antiviral agents are one of the most effective ways to control plant virus diseases. Ningnanmycin is currently the most successful anti-plant virus agent, but its field control effect is not ideal due to its instability. In recent years, great progress has been made in the research and development of antiviral agents, the mainstream research direction is to obtain antiviral agents or lead compounds based on structural modification of natural products. However, no antiviral agent has been able to completely inhibit plant viruses. Therefore, the development of highly effective antiviral agents still faces enormous challenges. Therefore, we reviewed the recent research progress of anti-plant virus agents based on natural products in the past decade, and discussed their structure-activity relationship (SAR) and mechanism of action. It is hoped that this review can provide new inspiration for the discovery and mechanism of action of novel antiviral agents.