Abstract
Two fenclorim derivatives (compounds 6 and 7) were synthesized by linking active sub-structures using fenclorim as the lead compound. The chemical structures of the two compounds were confirmed by NMR spectroscopy, high resolution mass spectrometry, and X-ray diffraction analysis. Their fungicidal activity against six plant fungal strains was tested. Compounds 6 and 7 both crystallized in the monoclinic system, with a P21/c space group (a = 8.4842(6) Å, b = 24.457(2) Å, c = 8.9940(6) Å, V = 1855.0(2) Å3, Z = 4) and Cc space group (a = 10.2347(7) Å, b = 18.3224(10) Å, c = 7.2447(4) Å, V = 1357.50(14) Å3, Z = 4), respectively. The crystal structure of compound 6 was stabilized by C–H···N and C–H···O hydrogen bonding interactions and N–H···N hydrogen bonds linked the neighboring molecules of compound 7 to form a three-dimensional framework. Compound 6 displayed the most excellent activity, which is much better than that of pyrimethanil against Botrytis cinerea in vivo. Additionally, compound 6 exhibited greater in vitro activity against Pseudoperonospora cubensis compared to that of pyrimethanil. Moreover, compound 7 exhibited strong fungicidal activity against Erysiphe cichoracearum at 50 mg/L in vitro, while pyrimethanil did not. Compounds 6 and 7 could be used as new pyrimidine fungicides in the future.
Highlights
Plant diseases caused by fungi can significantly affect the growth and development of crops such as potato, soybean, and rice, and reduce the yield (20% perennial yield losses and 10% postharvest losses) of crop plants globally [1,2,3,4]
Zheng et al [12] showed that fenclorim exhibited excellent in vivo fungicidal activity against Sclerotinia sclerotiorum, Fusarium oxysporum, Fusarium graminearum, and Thanatephorus cucumeris, and could be used as a lead compound to design novel pyrimidine-type fungicides
The fungicidal activities of compounds 6, 7, fenclorim and pyrimethanil against P. cubensis, E. cichoracearum, B. graminis, R. solani, and P. polysora were tested at different concentrations in vitro using methods reported previously [5]
Summary
Plant diseases caused by fungi can significantly affect the growth and development of crops such as potato, soybean, and rice, and reduce the yield (20% perennial yield losses and 10% postharvest losses) of crop plants globally [1,2,3,4]. A fenclorim derivative, named N-(4,6-dichloropyrimidine-2-yl) benzamide, was synthesized by inserting an amide group between the phenyl ring and the pyrimidine ring in fenclorim to study the activity relationship (SAR) against fenclorim This derivative displayed greater fungicidal activity than that of lead fenclorim and the positive control of pyrimethanil against. 2 2ofof 13 of pyrimethanil against Sclerotinia sclerotiorum and Fusarium oxysporum, with in vivo IC50 values of respectively. These indicateThese that the modification of fenclorim can produce highly active. These results indicate that the modification of fenclorim can produce highly active fungicidal compounds and that fenclorim provides broad potential as a lead compound for screening fungicides.
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