Intermediate Derivatization Method Research Articles

Discovery of new N-Phenylamide Isoxazoline derivatives with high insecticidal activity and reduced honeybee toxicity

Isoxazoline is a novel structure with strong potential for controlling agricultural insect pests, but its high toxicity to honeybees limits its development in agriculture. Herein, a series of N-phenylamide isoxazoline derivatives with low honeybee toxicity were designed and synthesized using the intermediate derivatization method. Bioassay results showed that these compounds exhibited good insecticidal activity. Compounds 3b and 3f showed significant insecticidal effects against Plutella xylostella (P. xylostella) with median lethal concentrations (LC50) of 0.06 and 0.07 mg/L, respectively, comparable to that of fluralaner (LC50 = 0.02 mg/L) and exceeding that of commercial insecticide fluxametamide (LC50 = 0.52 mg/L). It is noteworthy that the acute honeybee toxicities of compounds 3b and 3f (LD50 = 1.43 and 1.63 μg/adult, respectively) were significantly reduced to 1/10 of that of fluralaner (LD50 = 0.14 μg/adult), and were adequate or lower than that of fluxametamide (LD50 = 1.14 μg/adult). Theoretical simulation using molecular docking indicates that compound 3b has similar binding modes with fluralaner and a similar optimal docking pose with fluxametamide when binding to the GABA receptor, which may contribute to its potent insecticidal activity and relatively low toxicity to honey bees. This study provides compounds 3b and 3f as potential new insecticide candidates and provides insights into the development of new isoxazoline insecticides exhibiting both high efficacy and environmental safety.

A Potential Fungicide against Pseudoperonospora Cubensis: Design, Synthesis and 3D-QSAR of New Pyrazole-5-Carboxamide Derivatives.

Downy mildew is one of the major fungi causing significant economic losses to crops. The resistance of this fungus to current fungicides is increasing and new fungicides with a unique mode of action are needed. To find a novel pyrazole amide derivative as a potential fungicide. A series of pyrazole-5-carboxamide derivatives containing a diaryl ether were designed and synthesized by the Intermediate derivatization method (IDM). Their fungicidal activities against Pseudoperonospora cubensis (P. cubensis, cucumber downy mildew) were evaluated in the greenhouse. Bioassays indicated that several compounds exhibited excellent fungicidal activity against P. cubensis in vivo. In particular, T24 (EC50 = 0.88 mg L-1) had the highest activity compared with Dimethomorph and Fluazinam and other analogues. The relationship between the activity and the structure of these derivatives was analyzed, and an accurate and reliable three-dimensional quantitative structure-activity relationship (3D-QSAR) model was established to determine that electrostatic and steric fields had important effects on the improvement of fungicidal activity. The novel pyrazole-5-carboxamide derivative T24 can be considered a potential fungicide for P. cubensis control.

Design, synthesis and antifungal activities of novel cis-enamides via intermediate derivatization method

On the basis of the structure of natural product lansiumamide B (1), a total of 27 novel cis-enamide compounds were designed and synthesized via Intermediate Derivatization Method. Their chemical structures were characterized by 1H and 13C nuclear magnetic resonance and high-resolution mass spectrometry. The in vitro antifungal activities against Sclerotinia sclerotiorum, Thanatephorus cucumeris and Botrytis cinerea were evaluated by the mycelium linear growth rate method. Most of the compounds showed some activity against each of the fungi at 25 or 50 μg/mL. The relationship between structure and antifungal activity was also discussed, which showed the cinnamic double bond was critical to maintain the antifungal activity. Notably, among the title compounds, 3e and 3h could inhibit mycelia growth of Botrytis cinerea by approximately 50% (EC50) at 39.17 and 41.25 μg/mL respectively, which showed better antifungal activity than lansiumamide B (1) with more concise chemical structure. The present study pointed out the correct direction for the development and optimization of lansiumamide B derivatives as potential inhibitors of pathogenic fungi.

Discovery of Novel N-Pyridylpyrazole Thiazole Derivatives as Insecticide Leads

To develop effective insecticides against Lepidoptera pests, 25 novel N-pyridylpyrazole derivatives containing thiazole moiety were designed and synthesized based on the intermediate derivatization method (IDM). The insecticidal activities of these target compounds against Plutella xylostella (P. xylostella), Spodoptera exigua (S. exigua), and Spodoptera frugiperda (S. frugiperda) were evaluated. Bioassays indicated that compound 7g−7j exhibited good insecticidal activities. Compound 7g showed especially excellent insecticidal activities against P. xylostella, S. exigua, and S. frugiperda with LC50 values of 5.32 mg/L, 6.75 mg/L, and 7.64 mg/L, respectively, which were adequate for that of commercial insecticide indoxacarb. A preliminary structure-activity relationship analysis showed that the insecticidal activities of thiazole amides were better than that of thiazole esters, and the amides with electron-withdrawing groups on the benzene ring were better than the ones with electron-donating groups. This work provides important information for designing novel N-pyridylpyrazole thiazole candidate compounds and suggests that the 7g is a promising insecticide lead for further studies.

Synthesis, Anticancer Activities, and Mechanism of N-heptyl-containing Biguanide Derivatives.

In recent years, the anticancer effects of biguanide drugs have received considerable attention. However, the effective concentration of biguanide drugs to kill cancer cells is relatively high. Thus, we focus on structural modification of biguanides to obtain better antitumor candidates. A previous study in our laboratory has found that a biguanide compound containing the n-heptyl group has potent anticancer activity. However, the effect of different substituents on the benzene ringside of the biguanides on the anti-proliferative activity is unknown. A series of n-heptyl-containing biguanide derivatives whose benzene rings were modified by halogen substitution based on the intermediate derivatization method were further synthesized to find new compounds with improved antiproliferative activities. Ten n-heptyl-containing biguanide derivatives were synthesized via established chemical procedures. The activities of these derivatives were explored by MTT assay, clonogenic assay, and scratch assay. The protein levels were detected via Western blotting to explore the underlying mechanisms. The optimal biguanide derivatives 10a-10c, 11d exhibited IC50 values of 2.21-9.59 μΜ for five human cancer cell lines, significantly better than the control drug proguanil. The results of clonogenic and scratch wound healing assays also confirmed the inhibitory effects of derivatives 10a- 10c, 11d on the proliferation and migration of human cancer cell lines. Western blot results demonstrated that one representative derivative, 10c upregulates the AMPK signal pathway and downregulates mTOR/4EBP1/p70S6K. All biguanide derivatives containing n-heptyl groups are more active than proguanil, indicating that the modification of n-heptyl-containing biguanide derivatives provides a novel approach for the development of novel high efficient antitumor drugs.

A new potential aphicide against Myzus persicae: Design, synthesis and 3D-QSAR of novel phenoxypyridine derivatives containing 4-aminopyrimidine

Aphids are destructive insect pests that can cause substantial damage to crops due to their sap-sucking and transmission of plant virus. To find a new aphicide candidate, using the substituted phenoxypyridine alkyl amines as key intermediates, 31 novel phenyloxypyridine derivatives containing 4-aminopyrimidine were designed and synthesized by Intermediate Derivatization Method (IDM). The insecticidal activity of all target compounds were evaluated, and the bioassay results indicated that some compounds showed significant insecticidal activity against Myzus persicae (M. persicae) in vivo. Especially, the activity of T11 (LC50 = 0.34 mg⋅L − 1) was higher than that of Pymetrozine, Flufenerim and other derivatives, indicating that this compound was a promising aphicide candidate for further development. The structure-activity relationship (SAR) of these derivatives was also analyzed qualitatively. Furthermore, a three-dimensional quantitative structure-activity relationship (3D-QSAR) model was established with valuable guidelines that the electrostatic and steric fields played important roles on aphicidal activity. The present work provides helpful clues for the rational design of potential aphid control agents.

Design, synthesis, insecticidal activities, and molecular docking of novel pyridylpyrazolo carboxylate derivatives

AbstractBased on our previous work, using the strategies of “scaffold hopping” and “intermediate derivatization method” (IDM), a total of 44 novel pyridylpyrazolo carboxylate derivatives were designed and synthesized. The structures of these compounds were identified by 1H NMR and 13C NMR, and the insecticidal activities of the target compounds against Plutella xylostella and Spodoptera frugiperda were tested. Compound G35 showed the best insecticidal activities against P. xylostella (LC50 = 33.65 mg/L) and S. frugiperda (mortality rate = 61.21% at 100 mg/L). Preliminary structure–activity relationship analysis showed that the introduction of amino group and acetamide on the benzene ring helped to improve the insecticidal activity of the scaffold. Molecular docking model between compounds G34 or G35 and Ryanodine receptors (RyRs) of P. xylostella showed that RyRs may be a potential target of this series compounds and explained the difference in insecticidal activities. These findings provided guidance for further optimization of the pyridylpyrazolo carboxylate scaffold as potential insecticide.

Synthesis Candidates Herbicide Through Optimization Quinclorac Containing 3-Methyl-1H-pyrazol-5-yl.

To enhance quinclorac potency, twenty-five derivatives were synthesized containing 3-methyl-1H-pyrazol-5-yl by intermediate derivatization methods (IDMs). These compounds were confirmed by melting point (mp), 1HNMR, 13CNMR, and HRMS. The compound 1,3-dimethyl-1H-pyrazol-5-yl 3,7-dichloroquinoline-8-carboxylate (10a) was determined by X-ray diffraction. The activity of these compounds substituent on the phenyl was: electron-drawing group > neutral group > donor-drawing group, the results was like that of substituted benzyl group on pyrazole. The herbicidal activity assays showed that compounds 1-(2-fluorophenyl)-3-methyl-1H-pyrazol-5-yl 3,7-dichloroquinoline-8-carboxylate (8l, EC50 = 10.53 g/ha) and 10a (EC50 = 10.37 g/ha) had an excellent inhibition effect on barnyard grass in greenhouse experiment. Greenhouse safety experiment of rice exhibited almost no difference in plant height and fresh weight treated 10a at stage 1∼2-leaf of rice after 14 days but 8l had a detrimental effect. Two season field assays showed 10a herbicidal activity on barnyard grass at 150 g/ha as equal as 300 g/ha quinclorac in fields in 2019 and 2020. The study demonstrated that 10a could be further researched as a potential herbicide to control barnyard grass in fields.

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

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. 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 . 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.

Design, synthesis and herbicidal evaluation of novel uracil derivatives containing an isoxazoline moiety.

Glyphosate is the most widely used and successful herbicide discovered to date, but its utility is now threatened by the occurrence of several glyphosate-resistant weed species. Saflufenacil is a relatively new herbicide developed by BASF in 2010. It is a highly effective selective herbicide showing excellent control on broadleaf weeds (more than 90 species), significantly superior to other protoporphyrinogen oxidase (PPO) inhibitor herbicides at the level of weeds controlled. It is also effective against glyphosate-resistant Conyza canadensis if used in combination with glyphosate. A series of novel uracil-based PPO inhibitors containing an isoxazoline moiety were designed via the intermediate derivatization method, synthesized using a key saflufenacil raw material as starting material and evaluated for herbicidal activity. The target compounds were characterized by 1 H NMR and high-resolution electrospray mass spectra. Bioassays indicated that some title compounds can control efficiently and effectively both broadleaf weeds and grassy weeds at low doses, especially the glyphosate-resistant weeds C. canadensis and Eleusine indica. This work provides a basis for further studies of 9b for control of a wider range of weeds, particularly for glyphosate-resistant weeds.

Design, Synthesis, and Structure-Activity Relationship of Novel Spiropyrimidinamines as Fungicides against Pseudoperonospora cubensis.

Harmful fungus and the developed resistance to available fungicides seriously threaten the yield and quality of crops; thus, the search for new, highly efficient, and resistance-overcoming fungicides remains a quite urgent goal of agricultural scientists. In this study, a series of novel spiropyrimidinamine derivatives were designed and synthesized by employing the intermediate derivatization method (IDM). Their structures were identified by 1H NMR, elemental analyses, and MS spectra. The structure of compound 5 was further confirmed by X-ray diffraction. Bioassays indicated that a number of the title compounds exhibited some fungicidal activities against Pseudoperonospora cubensis. Especially, compound 5 displayed excellent activity (EC50 = 0.422 mg/L), significantly higher than those of the commercialized fungicides cyazofamid, flumorph, and diflumetorim. The structure-activity relationship was also discussed. It was concluded that compound 5 with super fungicidal potency and a novel structure is a promising agrochemical fungicide candidate for further development.

Synthesis, biological evaluation and anti-proliferative mechanism of fluorine-containing proguanil derivatives

Proguanil, a member of biguanide family, has excellent anti-proliferative activities. Fluorine-containing compounds have been demonstrated to have super biological activities including enhanced binding interactions, metabolic stability, and reduced toxicity. In this study, based on the intermediate derivatization methods, we synthesized 13 new fluorine-containing proguanil derivatives, and found that 7a,7d and 8e had much lower IC50 than proguanil in 5 human cancerous cell lines. The results of clonogenic and scratch wound healing assays revealed that the inhibitory effects of derivatives 7a,7d and 8e on proliferation and migration of human cancer cell lines were much better than proguanil as well. Mechanistic study based on representative derivative 7a indicated that this compound up-regulates AMPK signal pathway and downregulates mTOR/4EBP1/p70S6K. In conclusion, these new fluorine-containing derivatives show potential for the development of cancer chemotherapeutic drugs.

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

To explore a novel fungicide effectively against cucumber downy mildew (CDM), a series of new arylpyrazole containing pyrimidine ether derivatives were designed and synthesized by employing the intermediate derivatization method (IDM). The structures of synthesized compounds were identified by 1H NMR, 13C NMR, elemental analyses, MS, and X-ray diffraction. Bioassays demonstrated that some of the title compounds exhibited excellent fungicidal activities against CDM. Especially, compound 7 (EC50 = 1.22 mg/L) displayed significantly higher bioactivity than that of commercial fungicides diflumetorim and flumorph and nearly equal effect to that of cyazofamid. The relationship between the structure and fungicidal activity of the synthesized compounds was discussed as well. The study showed that compound 7 was a promising fungicide candidate for further development.

Design, synthesis, and fungicidal activity of novel 1,3,4-oxadiazole derivatives

Employing the intermediate derivatization method (IDM), twenty novel 1,3,4-oxadiazole derivatives containing arylpyrazoloxyl moiety were designed and synthesized. The structures of the title compounds were identified by 1H NMR, 13C NMR, MS and elemental analyses, compound 4 was further identified by single-crystal X-ray diffraction. Antifungal activities against rice sheath blight (RSB) and sorghum anthracnose (SA) were evaluated by the mycelium linear growth rate method. Compounds 4, 16 and 20 displayed significant activities against RSB (EC50=0.88mg/L, 0.91mg/L and 0.85mg/L, respectively), higher than the reference tebuconazole; While compound 3 exhibited higher activity against SA (EC50=1.03mg/L), equal to commercial pyraclostrobin (EC50=1.06mg/L). The study showed that compound 20 is a promising fungicide for further development.

Design, synthesis and antifungal activity of new substituted difluoromethylpyrimidinamine derivatives

Rusts are one of the most important fungal diseases, the known target sites have already developed serious resistance to the main existing classifications of fungicides. In order to discover novel fungicides with a promising activity on rusts, twenty new substituted difluoromethylpyrimidinamine derivatives were designed and synthesized with the aid of the intermediate derivatization methods starting from ethyl 4,4-difluoro-3-oxobutanoate that is the common raw material in some newly launched important succinate dehydrogenase inhibitor (SDHI) fungicides. Their structures were identified by 1H NMR, 13C NMR, 19F NMR, IR, elemental analyses and HRMS. All the compounds were screened for in vivo fungicidal activity against southern corn rust (SCR). The preliminary bioassay results indicated that 5-chloro-6-(difluoromethyl)-N-(2-(6-(3-(trifluoromethyl)phenoxy)pyridin-3-yl)ethyl)pyrimidin-4-amine (compoundJ, R1=CHF2, Alk=CH2CH2, Rn=3-CF3) is the optimal structure with desired fungicidal activity against SCR (EC50=2.16mg/L), significantly higher than commercial fungicides diflumetorim (EC50=53.26mg/L) and propiconazole (EC50=3.92mg/L). The structure–activity relationship of the synthesized compounds was discussed as well. This study also demonstrated that difluoromethylpyrimidinamine derivatives can be further utilized as a promising antifungal agent to control rust. Further synthesis and structure optimization studies are currently in progress.

Design, synthesis, and herbicidal activity of novel quaternary ammonium salt derivatives

A series of novel quaternary ammonium salt derivatives were designed and synthesized by introducing the herbicide carboxylic acid into substituted aminoacetanilide compounds which derived from herbicides alachlor or acetochlor, using the intermediate derivatization methods in an attempt to obtain novel candidates for weed control. The herbicidal activity assays in greenhouse demonstrated that some of the title compounds exhibited good herbicidal activities against velvet leaf, youth-and-old age, barnyard grass, and foxtail. Especially, III9 gave the best activity (EC50 (ga.i/ha): YOA 34.1, VEL 33.6, FOX 15.9, BYG 36.2). The field trials indicated that III9 had better herbicidal activity than the commercial herbicide imazethapyr to control broadleaf weeds at 150ga.i/ha. The present work demonstrated that the quaternary ammonium salt derivatives can be used as potential lead compounds for discovering novel herbicides with improved activity. III9 itself is worthy of being further developed as an herbicidal candidate. Further syntheses, structure optimization studies, and field trials around III9 are in progress.

Design, Synthesis, and Structure-Activity Relationship of New Pyrimidinamine Derivatives Containing an Aryloxy Pyridine Moiety.

The pyrimidinamine diflumetorim is an ideal template for the discovery of agrochemical lead compounds due to its unique mode of action, novel chemical structure, and lack of reported resistance. To develop a new pyrimidinamine fungicide effective against cucumber downy mildew (CDM), a series of new pyrimidinamine derivatives containing an aryloxy pyridine moiety were designed and synthesized by employing the recently reported intermediate derivatization method (IDM). The structures of all compounds were identified by 1H NMR, elemental analyses, HRMS, and X-ray diffraction. Bioassays demonstrated that some of the title compounds exhibited excellent fungicidal activities against CDM. Compound 9 gave the best activity (EC50 = 0.19 mg/L), which is significantly better than the commercial fungicides diflumetorim, flumorph, and cyazofamid. The relationship between structure and fungicidal activity of the synthesized pyrimidinamines was explored. The study showed that compound 9 is a promising fungicide candidate for further development.

Synthesis and antifungal activities of novel strobilurin derivatives containing quinolin-2(1H)-one moiety

To discover novel lead compounds with better antifungal activities, a series of novel strobilurin derivatives containing quinolin-2(1H)-one moiety was designed and synthesized via intermediate derivatization method. Their structures were characterized by means of 1H nuclear magnetic resonance(1H NMR), 13C NMR and high resolution mass spectrometry(HRMS). The biological assay results indicate that most target compounds exhibit good to excellent fungicidal activities against 10 plant pathogens. Compounds 4d, 5b and 5c possess 94.1%, 83.8% and 80.9% in vitro inhibition respectively against Rhizotonia cereals at the concentration of 50 μg/mL, which are better than that of the control agents. Especially, the inhibition activities of compound 4d against all of the tested fungi approach or exceed those of the controls. The structure-activity relationship was also discussed.

Discovery of flufenoxystrobin: Novel fluorine-containing strobilurin fungicide and acaricide

Abstract To discover new strobilurin analogues with high activity, a series of new fluorine-containing strobilurin derivatives were synthesized utilizing intermediate derivatization methods (IDM). The compounds were identified by 1 H and 19 F nuclear magnetic resonance (NMR), IR and elemental analysis. Preliminary bioassays in greenhouse indicated that compounds 2a (SYP-3759, flufenoxystrobin) and 2c exhibited excellent fungicidal activities against Erysiphe graminis protecting wheat at 1.56 mg L −1 concentration and compounds 2a showed a moderately high acaricidal activity at 10 mg L −1 . Field trials showed the fungicidal activities of compounds 2a and 2c is almost equivalent to that of pyraclostrobin, higher than that of triadimefon and the acaricidal activity of compound 2a is almost equivalent to that of pyidaben, but lower than that of fluacrypyrim. The preliminary mammalian toxicology results showed compound 2a was a low-toxicity compound. In conclusion compound 2a is a promising candidate for further development; mammalian toxicology and ecotoxicology with compound 2a are in progress.

Design, synthesis and insecticidal evaluation of aryloxy dihalopropene derivatives

Plutella xylostella (P. xylostella) is a highly migratory, cosmopolitan species and one of the most important pest of cruciferous crops worldwide. Pyridalyl as a novel class of insecticides has good efficacy against P. xylostella. On the basis of the commercial insecticide pyridalyl, a series of new aryloxy dihalopropene derivatives were designed and synthesized by using Intermediate Derivatization Methods. Their chemical structures were confirmed by 1H NMR, high-resolution mass spectrum (HRMS), and single-crystal X-ray diffraction analysis. The insecticidal activities of the new compounds against P. xylostella were evaluated. The results of bioassays indicated that most of the compounds showed moderate to high activities at the tested concentration, especially compounds 10e and 10g displayed more than 75% insecticidal activity against P. xylostella at 6.25mg/L, while pyridalyl showed 50% insecticidal activity at the same concentration. The field trials result of the insecticidal activities showed that compound 10e as a 10% emulsifiable concentrate (EC) was effective in the control of P. xylostella at 75–150g a.i./ha, and the mortality of P. xylostella for treatment with compound 10e at 75g a.i./ha was equivalent to pyridalyl at 105g a.i./ha.