Design, Synthesis, and Structure-Activity Relationship of New Arylpyrazole Pyrimidine Ether Derivatives as Fungicides

Discovery of novel Propionamide-Pyrazole-Carboxylates as Transketolase-inhibiting herbicidal candidates

BACKGROUND

Transketolase (TKL, EC 2.2.1.1) is a key enzyme in the pentose phosphate pathway and Calvin cycle, and is expected to act as a herbicidal site-of-action. On the basis of TKL, we designed and synthesized a series of 1-oxy-propionamide-pyrazole-3-carboxylate analogues and evaluated their herbicidal activities.

RESULTS

Methyl 1-methyl-5-((1-oxo-1-((4-(trifluoromethyl)phenyl)amino)propan-2-yl)oxy)-1H-pyrazole-3-carboxylate (C23) and methyl 1-methyl-5-((1-oxo-1-((perfluorophenyl)amino)propan-2-yl)oxy)-1H-pyrazole-3-carboxylate (C33) were found to provide better growth-inhibition activities against Digitaria sanguinalis root than those of nicosulfuron, mesotrione and pretilachlor at 200 mg L-1 using the small-cup method. These compounds were also identified as promising compounds in pre-emergence and postemergence herbicidal-activity experiments, with relatively good inhibitory effects toward Amaranthus retroflexus and D. sanguinalis at 150 g ai ha-1. In addition, enzyme inhibition assays and molecular docking studies revealed that C23 and C33 interact favourably with SvTKL (Setaria viridis TKL).

CONCLUSION

C23 and C33 are promising lead TKL inhibitors for the optimization of new herbicides. © 2024 Society of Chemical Industry.

Synthesis, acaricidal activity, and structure-activity relationships of novel phenyl trifluoroethyl thioether derivatives containing substituted benzyl groups

BACKGROUND

To discover and develop novel acaricidal compounds, a series of 2-fluoro-4-methyl/chlorine-5-((2,2,2-trifluoroethyl)thio)aniline/phenol compounds containing N/O-benzyl moieties were synthesized based on lead compound LZ-1.

RESULTS

The activity of these compounds against carmine spider mites (Tetranychus cinnabarinus) was determined using the leaf-spray method. Bioassays indicated that most of the designed target compounds possessed moderate to excellent acaricidal activity against adult T. cinnabarinus. The median lethal concentrations of 25b and 26b were 0.683 and 2.448 mg L-1 against adult mites, respectively; exceeding those of bifenazate (7.519 mg L-1 ) and lead compound LZ-1(3.658 mg L-1 ). Compound 25b exhibited 100% mortality in T. cinnabarinus larvae at 10 mg L-1 .

CONCLUSION

Continuing the study of these compounds in field trials, we compared the efficacy of mite killing by compound 25b with the commercial pesticide spirodiclofen and showed that mite control achieved 95.9% and 83.0% lethality at 10 and 22 days post-treatment. In comparison, spirodiclofen showed 92.7% lethality at 10 days and 77.2% lethality at 22 days post-treatment at a concentration of 100 mg L-1 . Results showed that 25b produced more facile and long-lasting control against T. cinnabarinus than the commercial acaricide spirodiclofen. Density functional theory analysis and electrostatic potential calculations of various molecular substitutions suggested some useful models to achieve other highly active miticidal compounds. © 2023 Society of Chemical Industry.

Design, synthesis, and fungicidal activity of novel N-substituted piperazine-containing phenylpyridines against cucumber downy mildew

BACKGROUND

Cucumber downy mildew (CDM) is a severe plant disease and affects the yield of cucumber production worldwide. As the resistance toward conventional fungicides is emerging as a ubiquitous issue, it is urgent to discover efficient fungicides with unique structures.

RESULTS

In this study, a series of novel phenylpyridine derivatives were designed and synthesized. Bioassays revealed that most of these compounds possessed excellent fungicidal activities against CDM. Among the phenylpyridine compounds, 2-(4-(4-(tert-butyl)benzyl)piperazin-1-yl)-6-phenylnicotinonitrile (C8) [half-maximal effective concentration (EC₅₀ ) = 4.40 mg L^-1 ] displayed the highest activity, which was better than those of the commercial fungicides, such as azoxystrobin (EC₅₀  = 42.77 mg L^-1 ) and flumorph (EC₅₀  = 41.94 mg L^-1 ). Furthermore, the molecular electrostatic potential of high-activity compound C8 indicated that nitrogen atom of the cyano group on the pyridine ring was in the negative region and may easily form hydrogen bonds and allow for electrostatic interactions with potential receptors.

CONCLUSIONS

This study demonstrated that the novel N-substituted piperazine-containing phenylpyridine derivatives could be further developed as a candidate compound to control CDM.

Synthesis and Antitumor Evaluation of Menthone-Derived Pyrimidine-Urea Compounds as Potential PI3K/Akt/mTOR Signaling Pathway Inhibitor

A series of novel menthone derivatives bearing pyrimidine and urea moieties was designed and synthesized to explore more potent natural product-derived antitumor agents. The structures of the target compounds were confirmed by FTIR, NMR, and HRMS. The in vitro antitumor activity was tested by standard methyl thiazolytetrazolium assay and showed that 4i, 4g, 4s, and 4m are the best compounds with IC50 values of 6.04 ± 0.62µM, 3.21 ± 0.67µM, 19.09 ± 0.49µM, and 18.68 ± 1.53µM, against Hela, MGC-803, MCF-7, and A549, respectively. The results of the preliminary action mechanism studies showed that compound 4i, the representative compound, could induce cell apoptosis in Hela cells in a dose-dependent manner and might arrest the cell cycle in the G2/M phase. Furthermore, the results of network pharmacology prediction and Western blot experiments indicated that compound 4i might inhibit Hela cells through inhibit PI3K/Akt/mTOR signaling pathway. The binding modes and the binding sites interactions between compound 4i and the target proteins were predicted preliminarily by the molecular docking method.

Synthesis, Anti-Tomato Spotted Wilt Virus Activities, and Interaction Mechanisms of Novel Dithioacetal Derivatives Containing a 4(3H)-Quinazolinone Pyrimidine Ring

A series of unreported novel dithioacetal derivatives containing a 4(3H)-quinazolinone pyrimidine ring were synthesized, and their antiviral activities were evaluated against tomato spotted wilt virus (TSWV). A three-dimensional quantitative structure-activity relationship (3D-QSAR) analysis was established, and compound D32 was designed and synthesized according to the analysis results of the CoMFA and CoMSIA models. The bioassay results showed that compound D32 exhibited excellent inactivation activity against TSWV, with EC₅₀ values of 144 μg/mL, which was better than those of ningnanmycin (149 μg/mL) and the lead compound xiangcaoliusuobingmi (525 μg/mL). The binding ability of compound D32 to TSWV CP was tested by microscale thermophoresis (MST), and the binding constant value was 4.4 μM, which was better than those of ningnanmycin (6.2 μM) and xiangcaoliusuobingmi (59.1 μM). Therefore, this study indicates that novel dithioacetal derivatives containing a 4(3H)-quinazolinone pyrimidine ring may be applied as new antiviral agents.

Construction of a Pyrimidine Framework through [3 + 2 + 1] Annulation of Amidines, Ketones, and N,N-Dimethylaminoethanol as One Carbon Donor

An efficient, facile, and eco-friendly synthesis of pyrimidine derivatives has been developed. It involves a [3 + 2 + 1] three-component annulation of amidines, ketones, and one carbon source. N,N-Dimethylaminoethanol is oxidized through C(sp³)-H activation to provide the carbon donor. One C-C and two C-N bonds are formed during the oxidative annulation process. The reaction shows good tolerance to many important functional groups in air, making this methodology a highly versatile alternative, and significant improvement to the existing methods for structuring a pyrimidine framework, especially 4-aliphatic pyrimidines.

Synthesis and Antifungal Activity of Pyrimidine Derivatives Containing an Amide Moiety

In this study, 17 novel pyrimidine derivatives containing an amide moiety were synthesized. Then their in vitro antifungal activities against Botryosphaeria dothidea (B. dothidea), Phomopsis sp., and Botrytis cinereal (B. cinereal) were determined. A preliminary biological test showed that compounds 5-bromo-2-fluoro-N-(2-((2-methyl-6-(trifluoromethyl)pyrimidin-4-yl)oxy)phenyl)benzamide (5f) and 5-bromo-2-fluoro-N-(3-((2-methyl-6-(trifluoromethyl)pyrimidin-4-yl)oxy)phenyl)benzamide (5o) exhibited higher antifungal activity against Phomopsis sp., with an inhibition rate of 100% compared to that of Pyrimethanil at 85.1%. In particular, compound 5o exhibited excellent antifungal activity against Phompsis sp., with the EC₅₀ value of 10.5 μg/ml, which was even better than that of Pyrimethanil (32.1 μg/ml). As far as we know, this is the first report on the antifungal activities against B. dothidea, Phomopsis sp., and B. cinereal of this series of pyrimidine derivatives containing an amide moiety.

Design, Synthesis and Antibacterial Activity of Novel Pyrimidine-Containing 4H-Chromen-4-One Derivatives*

A series of pyrimidine-containing 4H-chromen-4-one derivatives were designed and synthesized by combining bioactive substructures. Preliminary biological activity results showed that most of the compounds displayed significant inhibitory activities in vitro against Xanthomonas axonopodis pv. Citri (X. axonopodis), Xanthomonas oryzae pv. oryzae (X. oryzae) and Ralstonia solanacearum (R. solanacearum). In particular, compound 2-[(3-{[5,7-dimethoxy-4-oxo-2-(3,4,5-trimethoxyphenyl)-4H-1-benzopyran-3-yl]oxy}propyl)sulfanyl]-4-(4-methylphenyl)-6-oxo-1,6-dihydropyrimidine-5-carbonitrile (4c) demonstrated a good inhibitory effect against X. axonopodis and X. oryzae, with the half-maximal effective concentration (EC₅₀ ) values of 15.5 and 14.9 μg/mL, respectively, and compound 2-[(3-{[5,7-Dimethoxy-4-oxo-2-(3,4,5-trimethoxyphenyl)-4H-1-benzopyran-3-yl]oxy}propyl)sulfanyl]-4-(3-fluorophenyl)-6-oxo-1,6-dihydropyrimidine-5-carbonitrile (4h) showed the best antibacterial activity against R. solanacearum with an EC₅₀ value of 14.7 μg/mL. These results were better than commercial reagents bismerthiazol (BT, 51.7, 70.1 and 52.7 μg/mL, respectively) and thiodiazole copper (TC, 77.9, 95.8 and 72.1 μg/mL, respectively). In vivo antibacterial activity results indicated that compound 4c displayed better curative (42.4 %) and protective (49.2 %) activities for rice bacterial leaf blight than BT (35.2, 39.1 %) and TC (30.8, 27.3 %). The mechanism of compound 4c against X. oryzae was analyzed through scanning electron microscopy (SEM). These results indicated that pyrimidine-containing 4H-chromen-4-one derivatives have important value in the research of new agrochemicals.

Synthesis of Novel Pesticidal N,N'-Disubstituted Sulfamide Derivatives Using Sulfur(VI) Fluorine Exchange Click Reaction

Sulfur(VI) fluorine exchange click reaction was applied to the highly efficient synthesis of new N,N'-disubstituted sulfamide (R¹NH-SO₂-NHR²) derivatives as pesticide candidates. Bioassays were conducted to evaluate both insecticidal and fungicidal activities of the target compounds. Preliminary results showed that the target molecules exhibited good bioactivities. In particular, insecticidal activities of compounds D25 and D21 against Plutella xylostella (LC₅₀ = 2.42 and 3.87 μg·mL^-1) were superior or adequate to that of commercial insecticide indoxacarb (LC₅₀ = 3.99 μg·mL^-1). Moreover, some compounds could also exhibit satisfactory fungicidal activity toward plant pathogens Pyricularia grisea, Botrytis cinerea, and Thanatephorus cucumeris. This work could bring new insights into the application of heterocyclic N,N'-disubstituted sulfamides as novel pesticides.

Synthetic approaches to the 2015-2018 new agrochemicals

In this review, the synthesis of 33 agrochemicals that received an international standardization organization (ISO) name between January 2015 and December 2018 is described. The aim is to showcase the broad range and scope of reactions, reagents and intermediates used to discover and produce the latest active ingredients addressing the crop protection industry's needs.

Design, synthesis, and insecticidal activities of novel 5-substituted 4,5-dihydropyrazolo[1,5-a]quinazoline derivatives

BACKGROUND

Chemical pesticides are the main measures for pest control, but have caused growing resistance of pests and brought a series of environmental problems. Development of high-efficient insecticidal molecules with novel scaffolds is therefore particularly urgent.

RESULTS

Based on a [5 + 1] annulation reaction with 5-amino-1H-phenylpyrazole and dialkyl bromomalonate, 27 novel five-substituted 4,5-dihydropyrazolo[1,5-a]quinazolines were designed following the intermediate derivatization method and synthesized. Bioassay results indicated that most of the test compounds displayed good insecticidal activities against Plutella xylostella, Spodoptera frugiperda, and Solenopsis invicta. In particular, the insecticidal activities of compounds 4a, 4f, and 4m against P. xylostella [median lethal concentration (LC₅₀ ) values ranged from 3.87 to 5.10 mg L^-1 ] were comparable to that of indoxacarb (LC₅₀ = 4.82 mg L^-1 ). In addition, compounds 4a and 9e showed similar high insecticidal activities against Spodoptera frugiperda (mortality rate = 79.63% and 72.12%) at 100 mg L^-1 , comparable to that of fipronil (mortality rate: 68.44%); compound 9a showed possible delayed toxicity against Solenopsis invicta (mortality rate: 95.66%) after 5 days of treatment at 1.0 mg L^-1 .

CONCLUSION

Due to their high insecticidal activities against P. xylostella, compound 4m, 4a, and 4f could be considered as qualified candidates for novel insecticide. Several other 4,5-dihydropyrazolo[1,5-a]quinazolines with relatively high bioactivity, such as compounds 9a and 9e, are also worth further optimization as potential insecticide or anticide candidates.

Synthesis of Novel 6-Aryloxy-4-chloro-2-phenylpyrimidines as Fungicides and Herbicide Safeners

Fenclorim is a commercial herbicide safener with fungicidal activity used for chloroacetanilide herbicides, which might be suitable as a lead compound for screening novel fungicides. However, little has been reported so far on the structure-activity relationship of fungicidal activities of fenclorim or its analogues. Here, a series of 4-chloro-6-substituted phenoxy-2-phenylpyrimidine derivatives was synthesized by a substructure splicing route using fenclorim as a lead compound. The structures of synthesized derivatives were characterized by ¹H NMR, ¹³C NMR, and HRMS. Their fungicidal and herbicide safening activities were then evaluated. The results revealed that compound 11 had the best fungicidal activity against Sclerotinia sclerotiorum and Thanatephorus cucumeris, which was better than that of the control pyrimethanil. Moreover, compounds 3, 5, and 25 exhibited excellent safening activities against fresh weight, plant height, and root length, respectively. Such activities were significantly improved when compared to fenclorim. In summary, these findings look promising for the preparation of new fungicides and herbicide safeners based on the structure of fenclorim.

Diaryl Ether: A Privileged Scaffold for Drug and Agrochemical Discovery

Diaryl ether (DE) is a functional scaffold existing widely both in natural products (NPs) and synthetic organic compounds. Statistically, DE is the second most popular and enduring scaffold within the numerous medicinal chemistry and agrochemical reports. Given its unique physicochemical properties and potential biological activities, DE nucleus is recognized as a fundamental element of medicinal and agrochemical agents aimed at different biological targets. Its drug-like derivatives have been extensively synthesized with interesting biological features including anticancer, anti-inflammatory, antiviral, antibacterial, antimalarial, herbicidal, fungicidal, insecticidal, and so on. In this review, we highlight the medicinal and agrochemical versatility of the DE motif according to the published information in the past decade and comprehensively give a summary of the target recognition, structure-activity relationship (SAR), and mechanism of action of its analogues. It is expected that this profile may provide valuable guidance for the discovery of new active ingredients both in drug and pesticide research.

Design, Synthesis, and Anti-ToCV Activity of Novel Pyrimidine Derivatives Bearing a Dithioacetal Moiety that Targets ToCV Coat Protein

Novel pyrimidine sulfide derivatives containing a dithioacetal and strobilurin moiety were designed and synthesized. Their antiviral activities against tomato chlorosis virus (ToCV) were investigated through the tomato chlorosis virus coat protein (ToCVCP)-oriented screening method. Microscale thermophoresis was used to study the interaction between the compound and the ToCVCP. Compounds B13 and B23 interacted better with ToCVCP than the other compounds and had dissociation constant (Kd) values of 0.09 and 0.06 μM, respectively. These values were lower than those of the control agents, ningnanmycin (0.19 μM) and ribavirin (6.54 μM), which indicated that the compounds had a strong binding effect with ToCVCP. Quantitative real-time polymerase chain reaction was used to evaluate the role of compounds B13 and B23 in the gene regulation of ToCVCP. Both compounds significantly reduced the expression level of the ToCVCP gene in Nicotiana benthamiana with reduction values of 88 and 83%, which were better than those of ningnanmycin (65%) and lead compound C14 (73%). Pyrimidine sulfide containing a dithioacetal and strobilurin moiety is significant in the research and development of novel anti-ToCV agents.