O‐(2,6‐bis(4,6‐dimethoxypyrimidin‐2‐yloxy)benzoyl)oxime 3‐trifluoromethylacetophenone (HB‐002) was synthesized as potential acetolactate synthetase (ALS)‐inhibiting herbicides. HB‐002 was characterized by 1H nuclear magnetic resonance (NMR), 13C NMR, high resolution mass spectrometer (HRMS), and X‐ray single‐crystal diffraction. The herbicidal activities of HB‐002 against four weeds were studied in greenhouse. The results show that the control effects of HB‐002 on Eclipta prostrata L. and Cyperus difformis are very weak. However, HB‐002 exhibits higher herbicidal activity against Leptochloa chinensis (L.) Nees than that of Pyribenzoxim. HB‐002 also shows certain control effect on Echinochloa oryzoides (Ard.) Flritsch. Molecular docking simulation was performed to study the binding affinity and probable binding modes of HB‐002 with ALS. In the binding mode, the trifluoromethyl group of HB‐002 forms two halogen bonds (fluorine) with ALS, contributing to the lower binding free energy of HB‐002 (‐45.336 kcal/mol) as compared to Pyribenzoxim (‐40.1286 kcal/mol) and m‐trifluoromethyl Pyribenzoxim (‐44.451 kcal/mol). The present work suggests that HB‐002 may serve as a new candidate for potential herbicides.
in Wiley Online Library (wileyonlinelibrary.com). 9-Fluorenylmethoxycarbonyl was a good protecting group in the field of chemical industry. In the present paper, a new approach for the synthesis of oxadiazine insecticides indoxacarb used 9-fluorenylmethoxycarbonyl as protected group, and triphosgene for chloroformylation. A convenient synthesis of 9-fluorenylmethoxycarbonylhydrazine can be achieved by the nucleophilic substitution reaction of 9-fluorenylmethyl chloroformate and hydrazine hydrate. 4a-Methyl-2-(9-fluorenylmethyl)-7-chloro-indeno [1,2e][1,3,4]oxadia zine-2,4a (3H,5H)-dicarboxylate can be produced via ketone -hydrazine crosslink reaction and cyclization. A preparation of carbamic acid-(chlorocarbonyl)-[(4-trifluoromethoxy) phenyl] me ester can be obtained by the chloroformylation of triphosgene. Finally, the deprotection of 9-fluorenylmethoxy carbonyl and condensation with carbamic acid-(chlorocarbonyl)-[(4-trifluoromethoxy) phenyl] me ester can afford indoxacarb in good yield. A new method for the synthesis of oxadiazine insecticides indoxacarb used 9-fluorenylmethoxycarbonyl-protected group to produce 9-fluorenylmethoxycarbonylhydrazine, then through the ketone-hydrazine crosslink reaction, cyclization, deprotection, chloroformylation, and condensation in good yield.
A series of new trifluoromethyl-substituted phenyl alkyl ketoxime esters of Bispyribac were synthesized as potential herbicides. All synthesized compounds were characterized by nuclear magnetic resonance (NMR) spectroscopy and highresolution mass spectrometry (HRMS). Sprout method and foliar spray method were used to study the herbicidal activity of the synthesized compounds. Among all synthesized compounds, compound 3 (4-trifluoromethylphenyl n-butyl ketoxime ester of Bispyribac) exhibits the highest herbicidal activity against Echinochloa crusgalli (L.) Beauv with median effect dose (ED 50 ) of 1.7 μg/mL in pre-emergence herbicidal activity study. The structure-activity relationship analysis indicates that trifluoromethyl substitution on the phenyl group exhibits better activity than methoxy and methyl substitution on the phenyl group. The alkyl chain length also affects the activity significantly and the optimal alkyl chain length is four among the tested compounds. However, the substitution position of trifluoromethyl exhibits very limited influence on the activity. In post-emergence herbicidal activity study, compound 3 (ED 90 69.1056 g/hm 2 ) exhibits better herbicidal activity against Echinochloa crusgalli (L.) Beauv than Pyribenzoxim (ED 90 99.0810 g/hm 2 ). Moreover, compound 3 exhibits better safety to hybrid rice variety II you 084 and rice variety Nanjing 44 than Pyribenzoxim in crop safety study. Compound 3 may serve as a lead compound for future herbicide discovery.
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