Structure activity relationship on the herbicidal activity by the N-phenyl substituents of 2-(4-(6-chloro-2-benzoxazolyloxy)phenoxy)-N-Phenylpropionamide derivatives in down land

수답에서 2-(4-(6-chloro-2-benz-oxazolyloxy)phenoxy)-N-phenylpropionamide 유도체 중 N-phenyl 치환체들의 제초활성

  • Sung, Nack-Do (Department of Applied Biology and Chemistry, Chung-nam National University) ;
  • Lee, Sang-Ho (Department of Applied Biology and Chemistry, Chung-nam National University) ;
  • Ko, Young-Kwan (Korea Research Institute Chemical Technology) ;
  • Lee, Kyung-Mo (Korea Research Institute Chemical Technology) ;
  • Kim, Dae-Whang (Korea Research Institute Chemical Technology) ;
  • Kim, Tae-Joon (Korea Research Institute Chemical Technology)
  • 성낙도 (충남대학교 응용생물화학부) ;
  • 이상호 (충남대학교 응용생물화학부) ;
  • 고영관 (한국화학연구소 신물질연구부) ;
  • 이경모 (한국화학연구소 신물질연구부) ;
  • 김대황 (한국화학연구소 신물질연구부) ;
  • 김태준 (한국화학연구소 스크리닝연구부)
  • Published : 2000.06.30

Abstract

A new fourty six 2-(4-(6-chloro-2-benzoxazolyloxy)phenoxy)-N-phenylpro- pionamide derivatives were synthesized and the herbicidal activities against rice plant and barnyard grass with pre-emergence in down land were measured. The structure activity relationships (SAR) between the activities and physicochemical parameters of the substituted(X) N-phenyl group in substrates were analyzed and discussed by Free- Wilson and Hansch method from the basis on the former study (Sung. et. al., 1999). The conditions of selective herbicide activity both the barnyard grass and rice plant are shown that the optimal hydrophobicity, $({\pi})_{opt.}=1.34$ and electron donating with field effect (F<0) of meta and ortho, para-substituted mono or disubstituent on the N-phenyl ring were found to contribute significantly. The herbicidal activities against barnyard grass are roughly the same as the results in up land whereas damage to rice plant in down land more increase than that of up land. Degradation products in water are 2-(4-(6-chloro-2-benzoxazolyloxy)phenoxy)propionic acid ((A)) (obs. pKa=4.35 & obs. logP=4.77) and 6-chloro-2-benzoxazolone (B) (obs. pKa=8.40 & obs. logP=2.90). These results were supposing that the hydrolysis product of substrates, (A) is comparatively absorbed in rice plant but not in barnyard grass. And it is assumed from the SAR equations that the 2,6-dimethyl-4-methoxymethyl group substituent ($pI_{50}=5.41$, 3g/ha) is selected as the most highest herbicidal activity against barnyard grass in green house.

Keywords

2-(4-(6-chloro-2-benzoxazolyloxy)phenoxy)-N-phenylpropionamides;herbicidal activity;barnyard grass (Echinochloa crus-galli);pre-emergence;down land;QSAR;Hansch & Free-Wilson method;hydrolytic degradation