새로운 17종의 imazapyr 유도체인 3-(N-methyl-N(X)-치환-phenylaminooxoacetyl)-2-(4-isopropyl-5-oxo-2-imidazoline-2-yl)pyridine, 6을 합성하고 3-(N-methyl-N(X)-치환-phenylaminooxoacetyl group중의 X-치환기 변화에 따른 구조와 옥수수(Zea mays L.)와 참비듬(Amaranthus viridis L.)에 대한 발아 전의 제초활성에 미치는 관계(SAR)를 검토 한 바, 옥수수의 경우에는 MR상수의 적정값(optimal value)이 $5.56;cm^3/mol$이었으므로 이 값보다 크거나 작을수록 제초활성이 작았다. 참비듬의 경우에는 $L_1$상수의 적정값이 3.34 A이므로 이 값에 가까울수록 제초활성이 클 것임을 알 수 있었다. 특히, 2,5-difluoro group 치환체, 6i는 참비듬에 가장 큰 제초활성을 나타내었으나 옥수수에는 가장 작은 제초활성을 미치므로써 현저하게 두 초종간에 선택성을 나타내는 화합물이었다.
New seventeen imazapyr derivatives, 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-3-(N-methyl-N-X(sub.)-phenylaminooxoacetyl)pyridine, 6 were synthesized and their pre-emergence herbicidal activity$(pI_{50})$ in vivo against Corn (Zea mays L.) and Pigweed (Amaranthus viridis L.) were studied by the pot test under paddly conditions. Quantitative structure activity relationships (QSARs) were analyzed using the physicochemical parameters of substituent(X) on the phenyl ring of 3-(N-methyl-N-X(sub.)-phenylaminooxoacetyl) group and regression analysis. The herbicidal activities were related to the steric effect of X-substituent. The effect was rationalized by paraholic function of MR and $L_1$, where the optimal values were MR=5.56 (Zea mays L.) and $L_1=3.34;{{AA}}$ (Amaranthus viridis L.). Among them, 2,5-difluoro substituted compound, 6i showed good herbicidal activity against Pigweed with excellent tolerance to Corn.
