Design, Synthesis, Crystal Structure, and Fungicidal Activity of Two Fenclorim Derivatives

Abstract

<jats:p>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.</jats:p>

Synthesis of Novel 6-Aryloxy-4-chloro-2-phenylpyrimidines as Fungicides and Herbicide Safeners

“… 40 , 41 We previously evaluated the fungicide activity of fenclorim and proved it could be used as a fungicide-lead compound as this compound showed certain fungicide activity toward fungi such as Sclerotinia sclerotiorum , Fusarium oxysporum , Fusarium graminearum , and Thanatephorus cucumeris . 42 , 43 However, to the best of our knowledge, only a few reports have so far described the SAR of fungicidal activities of fenclorim or its analogues, indicating that more studies are needed. 44 Besides, it should be noted that these research studies revealed that strategic structural modifications of the chemical skeleton of fenclorim at the position of chlorine atom on the pyrimidine ring can yield novel molecules with new interesting properties.…”

“…Among all commercial herbicide safeners, fenclorim (4,6-dichloro-2-phenyl-pyrimidine) is a pyrimidine-type herbicide safener used for chloroacetanilide herbicides. , When fenclorim is soaked with rice seeds in pre-sowing applications or combination with chloroacetanilide herbicides on rice seedlings, it improves the tolerance of rice seedlings to chloroacetanilide herbicides. Fenclorim detoxifies herbicides by improving the GST expression, catalyzing the conjugation of chloroacetanilide herbicides with glutathione in rice. , We previously evaluated the fungicide activity of fenclorim and proved it could be used as a fungicide-lead compound as this compound showed certain fungicide activity toward fungi such as Sclerotinia sclerotiorum, Fusarium oxysporum, Fusarium graminearum, and Thanatephorus cucumeris. , However, to the best of our knowledge, only a few reports have so far described the SAR of fungicidal activities of fenclorim or its analogues, indicating that more studies are needed . Besides, it should be noted that these research studies revealed that strategic structural modifications of the chemical skeleton of fenclorim at the position of chlorine atom on the pyrimidine ring can yield novel molecules with new interesting properties…”

Iron-Catalyzed Highly para-Selective Difluoromethylation of Arenes

“…The synthetic utility of this system was further demonstrated by the synthesis of fluorinated fenclorim analogues (Scheme a), which are used to protect wet-sown rice from pretilachlor . Standard reaction conditions were readily scaled to 1 mmol, yielding the corresponding product 5i in 62% yield.…”