The discovery of HNPC-A3066: a novel strobilurin acaricide.

BACKGROUND: Although more than ten strobilurin analogues have been commercialized since 1996 as fungicides, only one was available as an acaricide as of 2003. To search for novel strobilurin analogues with unique biological activities, a synthetic screening programme was carried out. RESULTS: Syntheses of compounds analogous to the commercialized fungicide metominostrobin and the acaricide fluacrypyrim led to the discovery of a lead compound, (E)-2-[2-[[3,5-bis(trifluoromethyl)phenoxy]methyl]phenyl]-2-(methoxyimino)-N-methylacetamide (3b), that showed moderate acaricidal activity against Tetranychus urticae Koch. Compound 3b has a 3,5-(CF(3))(2)-phenoxymethyl group instead of the unsubstituted phenoxy substituent in metominostrobin. Optimization of compound 3b was achieved by introducing an oxime ether bridge along with an alkylthio(alkyl) branch in place of the oxymethylene chain between two aromatic moieties, as well as by replacing the methoxyiminoacetamide group with a methoxyacrylate structure, leading to (E)- methyl 2-[2-[[[(Z)[1-(3,5-bis(trifluoromethyl)phenyl)-2-methylthioethylidene]amino]oxy] methyl]phenyl]-3-methoxyacrylate (6c) and (E)- methyl 2-[2-[[[(Z)[1-(3,5-bis(trifluoromethyl)phenyl)-1-methylthiomethylidene]amino]oxy]methyl]phenyl]-3-methoxyacrylate (9a, HNPC-A3066). CONCLUSION: The above two compounds (6c, 9a) were shown to exhibit potent acaricidal and fungicidal activity. Compound 9a (HNPC-A3066) also exhibits larvicidal and ovicidal activities against various acarids. The acaricidal potency is comparable with those of commercial acaricides such as fluacrypyrim, tebufenpyrad and chlorfenapyr.

Synthesis and fungicidal activities of novel bis(trifluoromethyl)phenyl-based strobilurins.

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.

[Changes of DIMBOA contents in resistant and susceptible wheat near-isolines infected by Puccinia striiformis f. sp. tritici].

With two sets of wheat near-isolines having different genetic background as test materials, this paper studied the dynamics of their DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one) contents during Puccinia striiformis f. sp. tritici infection. It was revealed that in un-inoculated plants, no significant difference was observed in DIMBOA contents among various resistant and susceptible inbred lines within the same set. But, at the initial stage of infection, the DIMBOA contents in all resistant isolines displayed a quicker and greater increase, resulting in a significantly higher content of DIMBOA in resistant isolines than in susceptible one throughout the period of disease development. The infection ultimately led to a decline of DIMBOA contents in all infected plants, but the decrement was significantly less in resistant lines than in susceptible one. It could be concluded that DIMBOA was associated with the monogenic resistance to Puccinia striiformis f. sp. tritici in wheat. The study of DIMBOA dynamics in plants suffered from diseases and pests would be useful for understanding the mechanism of resistance, and the screening and breeding of crop varieties with multiple-resistance.

Synthesis and insecticidal activities of novel oxime ether pyrethroids.

A series of novel 2-methylthio-3'/4'-substituted acetophenone oxime O-ethers were synthesized by the reaction of the corresponding acetophenone oximes with halides of pyrethroid alcohols in the presence of sodium hydroxide and phase-transfer catalysis or with triethyl quaternary ammonium salts of halides of pyrethroid alcohols in the presence of sodium hydroxide. These compounds showed notable insecticidal activity against Homopteran and Lepidopteran pests. 2-Methylthio-4'-fluoroacetophenone oxime O-[(2-methylbiphenyl-3-yl)methyl] ether was more effective than the commercial insecticides chlorfenapyr and fenvalerate.