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1.
J Agric Food Chem ; 71(8): 3742-3750, 2023 Mar 01.
Article in English | MEDLINE | ID: mdl-36802621

ABSTRACT

To search for novel pesticides, the synthesis around commercialized insecticide tebufenpyrad accidentally led us to the discovery of the fungicidal lead compound, 3-ethyl-1-methyl-N-((2-phenylthiazol-4-yl)methyl)-1H-pyrazole-5-carboxamide (1a) and its pyrimidin-4-amine-based optimization derivative 5-chloro-2,6-dimethyl-N-(1-(2-(p-tolyl)thiazol-4-yl)ethyl)pyrimidin-4-amine (2a). Compound 2a not only demonstrates fungicidal activity superior to commercial fungicides such as diflumetorim but also exhibits the good features that come with pyrimidin-4-amines, such as unique modes of action and no cross-resistance to other pesticide classes. However, 2a is highly toxic to rats. Further optimization of 2a by introducing pyridin-2-yloxy substructure finally led to the discovery of 5b5-6 (HNPC-A9229) (5-chloro-N-(1-((3-chloropyridin-2-yl)oxy)propan-2-yl)-6-(difluoromethyl)pyrimidin-4-amine). HNPC-A9229 exhibits excellent fungicidal activities with EC50 values of 0.16 mg/L against Puccinia sorghi and 1.14 mg/L against Erysiphe graminis, respectively. Not only that its fungicidal potency is significantly superior to or comparable to commercial fungicides including diflumetorim, tebuconazole, flusilazole, and isopyrazam, HNPC-A9229 possesses low toxicity to rats.


Subject(s)
Fungicides, Industrial , Animals , Rats , Fungicides, Industrial/pharmacology , Fungicides, Industrial/chemistry , Amines , Structure-Activity Relationship
2.
Bioorg Med Chem Lett ; 29(11): 1430-1433, 2019 06 01.
Article in English | MEDLINE | ID: mdl-30975625

ABSTRACT

A series of nitropyridyl-based dichloropropene ethers were prepared and evaluated for their insecticidal activities against main lepidopteran pests such as M. separate, P. xylostella and P. litura. The compounds showed a broad-spectrum of remarkable insecticidal activities. Especially 4a (2,6-dichloro-4-(3,3-dichloroallyloxy)phenyl 3-[5-nitro-2-pyridyloxy]propyl ether) and 11a (2-(4-(3-(2,6-dichloro-4-((3,3-dichloroallyl)oxy)phenoxy)propoxy)phenoxy)-5-nitropyridine) displayed potent activities comparable to that of Pyridalyl, the only commercialized dichloropropene ether insecticide thus far. The structure-activity relationship was also discussed.


Subject(s)
Ethers/pharmacology , Insecticides/pharmacology , Pyridines/pharmacology , Animals , Ethers/chemical synthesis , Insecticides/chemical synthesis , Molecular Structure , Moths/drug effects , Pyridines/chemical synthesis , Structure-Activity Relationship
3.
J Agric Food Chem ; 57(20): 9585-92, 2009 Oct 28.
Article in English | MEDLINE | ID: mdl-19772294

ABSTRACT

A carboxylic ester group was introduced to three series of isoindolinedione substituted benzoxazinone derivatives. Some of these analogues exhibited good herbicidal activities, and the injury symptoms against weeds included leaf cupping, crinkling, bronzing, and necrosis, typical of protox inhibitor herbicides. Structurally, they were classified as Chemical Group A (4-carboxylic ester group-6-isoindolinyl-benzoxazinones), B (4-carboxylic ester group-7-isoindolinyl-benzoxazinones), and C (4-carboxylic ester group-6- tetrahydroisoindolinyl-benzoxazinones). All of the tested compounds were structurally confirmed by (1)H NMR, IR, mass spectroscopy, and elemental analysis. Preliminary bioassay data of these three classes of compounds showed that, in general, the order of the herbicidal effectiveness is C > A > B. Several of the lead compounds, for example, C10 (methyl 2-(6-(1,3-dioxo-4,5,6,7-tetrahydro-1H-isoindol-2(3H)-yl)-7-fluoro-2-methyl-3-oxo-2H-benzo[b][1,4] oxazin-4(3H)-yl) propano-ate), C12 (ethyl 2-(6-(1,3-dioxo-4,5,6,7-tetrahydro-1H-isoindol-2(3H)-yl)-7-fluoro-2- methyl-3-oxo-2H-benzo[b][1,4]oxazin-4(3H)-yl) propanoate), and C13 (ethyl 2-(6-(1,3-dioxo-4,5,6,7-tetrahydro-1H-isoindol-2(3H)-yl)-7-fluoro-2-methyl-3-oxo-2H-benzo-[b][1,4]oxazin-4(3H)-yl) butanoate), exhibited greater than 80% control at 75 g a.i./ha in both pre- and postemergence treatments against dicotyledonous weeds, such as Abutilon theophrasti Medic, Chenopodium album L., and Amaranthus ascendens L., and monocotyledon weeds, such as Digitaria sanguinalis L., Echinochloa crus-galli L., and Setaria viridis L. On the basis of advanced screening tests and crop selectivity, compounds C10, C12, and C13 are safer to crops than flumioxazin. Compounds C10, C12, and C13 are potent to develop as pre-emergent herbicides used in peanut, soybean, maize, and cotton fields.


Subject(s)
Herbicides/chemistry , Herbicides/pharmacology , Herbicides/chemical synthesis , Magnoliopsida/drug effects , Molecular Structure , Structure-Activity Relationship
4.
J Agric Food Chem ; 56(15): 6562-6, 2008 Aug 13.
Article in English | MEDLINE | ID: mdl-18598043

ABSTRACT

Strobilurins have become one of the most important classes of agricultural fungicides. To search for novel strobilurin compounds with unique biological activities, novel bis(trifluoromethyl)phenyl-based strobilurin analogues were synthesized by the reaction of 1-bis(trifluoromethyl)phenyl based methanone oxime with corresponding strobilurin pharmacophores in the presence of bases such as potassium hydroxide, potassium carbonate, or sodium hydride. ( E)-Methyl 2-(2-(((( Z)(1-(3,5-bis(trifluoromethyl) phenyl)-1-methoxymethylidene)amino)oxy)methyl)phenyl)-3-methoxyacrylate and ( Z)-methyl- N-( E)-2-(( E)-(5,6-dihydro-1,4,2-dioxazin-3-yl)(methoxyimino)methyl)benzyloxy-3,5-bis(trifluoromethyl)benzimidate were more effective against Erysiphe graminis and sphaerotheca fuligine than commercial strobilurin fungicides metominostrobin, azoxystrobin, and trifloxystrobin.


Subject(s)
Fungicides, Industrial/chemical synthesis , Fungicides, Industrial/pharmacology , Methacrylates/chemical synthesis , Methacrylates/pharmacology , Ascomycota/drug effects , Structure-Activity Relationship
5.
Acta Crystallogr Sect E Struct Rep Online ; 64(Pt 1): o8, 2007 Dec 06.
Article in English | MEDLINE | ID: mdl-21200957

ABSTRACT

The title compound, C(21)H(22)N(2)O(3), was synthesized by the reaction of tert-butyl-hydrazine with phthalic anhydride and further O-benzoyl-ation of the resulting inter-mediate by 3,5-dimethyl-benzoyl chloride. Inter-molecular C-H⋯O=C inter-actions link the mol-ecules into layers.

6.
J Agric Food Chem ; 53(20): 7908-14, 2005 Oct 05.
Article in English | MEDLINE | ID: mdl-16190649

ABSTRACT

The mode of action of 2-(7-fluoro-3-oxo-3,4-dihydro-2H-benzo[b][1,4]oxazin-6-yl)-4,5,6,7-tetrahydro-2H-isoindoline-1,3-diones, including the commercial herbicide flumioxazin, had been identified as inhibition of protoporphyrinogen oxidase (protox). As part of continuous efforts to search for new herbicides with high efficacy, broad-spectrum activity, and safety to crops, flumioxazin and its iodo analogue (B2055) were used as lead compounds for further optimization. Series of novel compounds were prepared by multistep synthetic procedures starting from 5-fluoro-2-nitrophenol. All of the test compounds were structurally confirmed by 1H NMR, IR, mass spectroscopy, and elemental analysis. Preliminary bioassay data showed that some of them possess commercial levels of herbicidal activity comparable to those of other protox-inhibiting herbicides. One of the best compounds, 5-fluoro-2-(7-fluoro-3-oxo-4-(prop-2-ynyl)-3,4-dihydro-2H-benzo[b][1,4]oxazin-6-yl)isoindoline-1,3-dione (8e), has IC50 values for velvetleaf (Abutilon theophrasti Medic) and crabgrass (Digitaria sanguinalis) comparable to thos of B2055. With respect to crop selectivity, compound 8e is similar to flumioxazin. Compound 8e is safe to cotton and maize at a rate of 150 g of active ingredient (ai)/ha or less when applied at pre-emergent stage, and it has the best safety to wheat among the tested crops, showing no injury after post-emergent application at 7.5-30 g of ai/ha.


Subject(s)
Herbicides/chemical synthesis , Herbicides/pharmacology , Oxazines/chemical synthesis , Oxazines/pharmacology , Benzoxazines , Phthalimides/chemical synthesis , Phthalimides/pharmacology , Plants/drug effects , Structure-Activity Relationship
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