Synthesis and Herbicidal Activity of 3-Aryl-5-(haloalkyl)-4-isoxazolecarboxamides and Their Derivatives

• Published in: Journal of agricultural and food chemistry Vol. 43; no. 1; pp. 219 - 228
• Main Authors: Hamper, Bruce C, Leschinsky, Kindrick L, Massey, Steven S, Bell, Crystal L, Brannigan, Lawrence H, Prosch, S. Douglas
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 01.01.1995; Amer Chemical Soc
• Subjects: Agriculture; Agriculture, Multidisciplinary; AMIDAS; AMIDE; AZOLE; AZOLES; Biological and medical sciences; Chemistry; Chemistry, Applied; DOSAGE BIOLOGIQUE; ENSAYO BIOLOGICO; Food Science & Technology; Fundamental and applied biological sciences. Psychology; Generalities. Disease free stocks; HERBICIDAS; HERBICIDE; Life Sciences & Biomedicine; Physical Sciences; Phytopathology. Animal pests. Plant and forest protection; Science & Technology; HERBICIDE; ISOXAZOLECARBOXAMIDE; CYCLOADDITION; ISOXAZOLE; FLUOROALKYL; Cycloaddition; Isoxazole derivatives; Structure activity relation; Chemical synthesis; Herbicide
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf00049a040

A series of unique 3-aryl-5-(haloalkyl)-4-isoxazolecarboxamides have been prepared which exhibit, in both greenhouse and field studies, significant preemergent and postemergent herbicidal activity in the grams per hectare range against broadleaf and narrowleaf weeds. The key step in the formation of the fully substituted isoxazole ring 2 is 1,3-dipolar cycloaddition of a haloalkyl-substituted acetylenic ester and a nitrile oxide intermediate. The 3-aryl-5-(haloalkyl)-4-isoxazole-carboxylate esters 2 are converted to isoxazole-4-carboxamide herbicides 5 and 6, secondary amides 7, and amino acid derivatives 8. Greatest activity was observed with compounds having a combination of three substituents: a substituted phenyl ring in the 3-position, a primary or secondary carboxamide in the 4-position, and a difluorochloromethyl group in the 5-position of the isoxazole ring