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Measuring Rates of Herbicide Metabolism in Dicot Weeds with an Excised Leaf Assay
Published on: September 7, 2015
New herbicide models from benzoxazinones: aromatic ring functionalization effects.
Francisco A Macías1, João M De Siqueira, Nuria Chinchilla
1Grupo de Alelopatía, Departamento de Química OrgAnica, Universidad de CAdiz, Avenida República Saharaui s/n, 11510 Puerto Real, CAdiz, Spain. famacias@uca.es
Journal of Agricultural and Food Chemistry
|December 21, 2006
Summary
Researchers explored new herbicide candidates by modifying benzoxazinone structures. Fluorination at specific aromatic positions, particularly C-7, yielded the most potent and selective herbicidal compounds against weeds like Lolium rigidum and Avena fatua.
Area of Science:
- Agrochemicals
- Organic Chemistry
- Plant Science
Background:
- Benzoxazinones are a promising scaffold for herbicide development.
- Previous research optimized functionalization at C-2 and N-4 positions.
- Further optimization requires exploring substitutions on the aromatic ring.
Purpose of the Study:
- To synthesize novel benzoxazinone derivatives with aromatic substitutions.
- To evaluate the phytotoxicity of these derivatives against standard target species and weeds.
- To correlate structural modifications with herbicidal activity and selectivity.
Main Methods:
- Synthesis of benzoxazinone derivatives with various aromatic substituents (methoxy, methoxycarbonyl, halogens, trifluoromethyl).
- Phytotoxicity assays on selected standard target species and weeds.
- Correlation analysis of activity with molecular parameters (steric, electronic, volume, dipole moment).
- Selectivity index calculation based on dose-response profiles.
Main Results:
- Aromatic substitutions, especially halogenations at C-6 and fluorination at C-7, enhanced phytotoxicity.
- Compounds 6-fluoro-(2H)-1,4-benzoxazin-3(4H)-one (6F-D-DIBOA), 7-fluoro-(2H)-1,4-benzoxazin-3(4H)-one (7F-D-DIBOA), and 6-chloro-(2H)-1,4-benzoxazin-3(4H)-one (6Cl-D-DIBOA) exhibited high activity.
- Molecular volume and dipole moment were key parameters influencing phytotoxicity.
- 7F-D-DIBOA demonstrated the highest selectivity between wheat and its common weeds.
Conclusions:
- Aromatic substitution is a viable strategy for developing potent benzoxazinone herbicides.
- Fluorination at C-7 offers a promising route for selective weed control.
- Further research into structure-activity relationships can optimize herbicide design.
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