• The Korean Journal of Pesticide Science
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• v.4 no.3
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• pp.34-39
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• 2000

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.

• Applied Biological Chemistry
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• v.49 no.3
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• pp.238-242
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• 2006

The herbicidal activities against the pre-emergence of rice plant (Oryza sativa L.) and barnyard grass (Echinochloa crus-gall) with changing substituents $(R_1-R_4)$ of new 5-benzofuryl-2-[1-(alkoxyimino) alkyl]-3-hydroxycyclohex-2-en-1-one derivatives as substrate molecules were studied quantitatively using comparative molecular field analyses (CoMFA). The optimized CoMFA models (rice plant: A5 & barnyard grass: B3) were derived from atom based fit alignment and a combination of CoMFA fields. The two models for herbicidal activity against two plants showed the best predictability and fitness ($q^2$>0.6 & ${r^2}_{ncv.}$>0.94) for the herbicidal activities. Also, CoMFA-HINT contour maps showed that the selective herbicidal activity between rice plant and barnyard grass depends on the hydrophobicity of $R_2\;and\;R_3$ groups in molecule. Therefore, it is expected that the herbicidal activity against barnyard grass will be improved by the introduction of the steric bulk small and hydrophobic group.

• The Korean Journal of Pesticide Science
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• v.12 no.1
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• pp.9-17
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• 2008

QSARs (Quantitative structure-activity relationships) between a series of new cyclohexanedione derivatives (5-benzofuryl-2-[1-(alkoxyimino)-alkyl]-3-hydroxycyclohex-2-en-1-ones) and their herbicidal activity against Rice plant (Oryza sativa L.) and Barnyard grass (Echinochloa crus-galli.) were discussed quantitatively using 2D-QSAR and holographic (H) QSAR methods. Generally, the HQSAR models have better predictability and fitness than the 2D-QSAR models. The herbicidal activities against Barnyard grass with 2D-QSAR II model were dependent upon Balaban indice (BI) of molecule and hydrophobicity of $R_1$ and $R_3$ group. And also, the $R_3=ethyl$ group, according to the information of the optimized HQSAR IV model, was more contribute to the herbicidal activities against Rice plant, while the 5-(cyclohex-3-enyl)-2,3-dihydrobenzofuran ring part was not contribute to the herbicidal activities against two plants.

• The Korean Journal of Pesticide Science
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• v.10 no.1
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• pp.7-14
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• 2006

Three-dimensional quantitative structure-activity relationships (3D-QSARs) on the herbicidal activities against in-vitro pre-emergence rice plant (Oryza sativa L.) and barnyard grass (Echinochloa crus-galli) by new 5-benzofuryl-2-[1-(alkoxyimino)alkyl]-3-hydroxycyclohex-2-en-1-one derivatives were studied quantitatively using comparative molecular similarity indices analysis (CoMSIA) methodology. The optimized CoMSIA model(A5: $r^2_{cv.}=0.569$ & $r^2_{ncv.}=0.941$) for rice plant exhibited a good correlation with steric (31.6%) and hydrophobic (39.7%) factors of the substrate molecules, and the model (B4: $r^2_{cv.}=0.569$ & $r^2_{ncv.}=0.941$) for barnyardgrass exhibited a good correlation with electrostatic (46.7%) and H-bond acceptor field (30.8%), respectively. The predicted $R_1=SF_5,\;R_2=R_3=R_4=H(P1)$ substituent (Rice plant: $pI_{50}=4.84$ & Barnyardgrass: $pI_{50}=7.21$, ${\Delta}pI_{50}=2.37$) by the model (B4) not only exhibited to the highest herbicidal activity against barnyardgrass, but also exhibited to the highest selecticity between two plants.