15종의 새로운 5-benzofuryl-2-[1-(alkoxyimino)alkyl]-3-hydroxycyclohex-2-en-1-one 유도체 중, 2,3-dihydro-2-ethyl-2,4,6,7-tetramethylbenzofuran-5-yl 치환체들을 합성하고 벼 (Oryza sativa L.) 씨앗과 3엽기 그리고 발아 후, 물피 (Echinochloa crus-galli)에 대한 제초활성을 측정한 바, 전체적으로 $R_{1}$=ethyl 치환체, $1{sim}8$이 비교적 큰 제초활성을 나타내었다. Azomethine 결합의 N 원자상 alkoxy-치환체 ($OR_{2}$)가 변화함에 따른 구조와 제초활성과의 관계 (SAR)를 정량적으로 검토하였다. 그 결과, 벼는 입체효과에 그리고 물피는 소수성에 의존적이었다. 두 초종간 선택성의 조건은 적정값의 소수성, $(logP)_{opt.}=6.0$을 가지며 분자의 길이 (L)에 관여하는 $R_{2}$의 길이는 길고 폭 (B)에 관여하는 $R_{1}$은 작아야 할 것으로 설명되었다.
A new fifteen 2,3-dihydro-2-ethyl-2,4,6,7-tetramethylbenzofuran-5-yl substituents in 5-benzofuryl-2-[1-(alkoxyimino)alkyl]-3-hydroxycyclohex-2-en-1-one derivatives as substrate were synthesized and their herbicidal activities against rice plant (Oryza sativa L.) and barnyard grass (Echinochloa crus-galli) with post emergence were measured under submerged conditions. The $R_{1}$=methyl substituents, $1{sim}8$ showed the higher herbicidal activity to the rice plant and barnyard grass. The structure-activity relationships (SARs) on tile herbicidal activity of $R_{1}$ and $OR_{2}$ groups on the azomethine bond in substrates were analysized. From tile results of dicussed SAR, the herbicide activities against rice plant would depend largely on the steric factor, Whereas, in case of barnyard grass, the activities were governed by the hydrophobicity factor. The conditions of selective herbicide activity between the two plant species are assumed that the substrates should nave optimal hydrophobicity ( $(logP)_{opt.}=6.0$), a $R_{1}$ groups of small and a long $OR_{2}$ groups.
