Structure-activity relationships on the herbicidal activity of the 2,3-dihydro-2,2,4,6,7-pentamethylbenzofuran-5-yl substituents in 5-benzofuryl-2-[1-(alkoxyimino)alkyl]-3-hydroxycyclohex-2-en-1-one derivatives

5-Benzofuryl-2-[1-(alkoxyimino)alkyl]-3-hyoxycyclohex-2-en-1-one 유도체 중 2,3-dihydro-2,2,4,6,7-pentamethylbenzofuran-5-yl 치환체들의 제초활성에 관한 구조-활성관계

A some of synthesized 2,3-dihydro-2,2,4,6,7-pentamethylbenzofuran-5-yl substituents in 5-benzofuryl-2-[1-(alkoxyimino)alkyl]-3-hydroxycyclohex-2-en-1-one derivatives as substrates were found to show herbicidal activity against rice plant (Oryza sativa L.) and barnyard grass (Echinochloa crus-galli) with post emergence under submerged conditions. The substrate with $R_{1}$=methyl substituents, $1{\sim}5$ showed the higher herbicidal activity to the seed, 3 leaf stage of rice plant and barnyard grass. The structure activity relationships (SARs) on the herbicidal activity of $R_{1}$ and $R_{2}$ on the azomethine bond in substrate were analysized. In the condition of $R_{1}$ groups are same, the herbicidal activity against 3 leaf stage of rice plant were governed by the optimal hydrophobicity $(logP)_{opt.}=4.57$. Whereas, in the case of barnyard grass, the herbicidal activities were largely dependent upon the steric effect, $B_{2}$ constant than hydrophobicity. In order to take the selective herbicidal activity between rice plant and barnyard grass, it is assumed that the (S) should be a round shape with higher hydrophobicity (logP>4.57) than optimal value. Also, the $R_{1}$ groups must be small and the $R_{2}$ groups are advisable to be unsaturate.

일련의 5-benzofuryl-2-[1-(alkoxyimino)alkyl]-3-hydroxycyclohex-2-en-1-one 유도체, (S)중 2,3-dihydro-2,2,4,6,7-pentamethylbenzofuran-5-yl 치환체들의 발아 전 후의 벼 (씨앗 및 3엽기)와 물피 (Echinochloa crus-galli)에 대한 제초활성을 측정한 바, $R_{1}$=methyl 치환체, $1{\sim}5$가 비교적 우수한 제초활성을 나타내었다. Azomethine 결합치 N 원 자상 alkoxy ($R_{2}$)기가 변화함에 따른 구조와 제초활성과의 관계 (SAR)를 정량적으로 검토한 결과, $R_{1}$이 모두 동일하다는 가정하에 벼의 3엽기에는 (S)가 소수성에 의존적으로 적정값, $(logP)_{opt.}=4.57$을 가질 경우에 약해가 가장 클 것이며 물피에 대한 경우에는 소수성보다 $B_{2}$값에 더 의존적이었다. 두 초종에 대한 선택성 조건으로 (S)는 적정값보다 큰 소수성 (logP>4.57)과 길이 (L)와 폭 (B)이 큰 원형이어야 하고 $R_{1}$-치환기는 작아야하며 $R_{2}$-기는 불포화되어야 할 것으로 예상되었다.