Synthesis and Herbicidal Activity of 2-(7-Fluoro-3-oxo- 3,4-dihydro-2H-benzo[b][1,4]oxazin-6-yl)isoindoline-1,3-diones

• Published in: Journal of agricultural and food chemistry Vol. 53; no. 20; pp. 7908 - 7914
• Main Authors: Huang, Ming-zhi, Huang, Ke-long, Ren, Ye-guo, Lei, Man-xiang, Huang, Lu, Hou, Zhong-ke, Liu, Ai-ping, Ou, Xiao-ming
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 05.10.2005; Amer Chemical Soc
• Subjects: Abutilon theophrasti; Agriculture; Agriculture, Multidisciplinary; Benzoxazines; Biological and medical sciences; Chemistry; Chemistry, Applied; corn; cotton; Digitaria sanguinalis; Food industries; Food Science & Technology; Fundamental and applied biological sciences. Psychology; Gossypium hirsutum; herbicidal properties; herbicides; Herbicides - chemical synthesis; Herbicides - pharmacology; Life Sciences & Biomedicine; nontarget organisms; organofluorine compounds; Oxazines - chemical synthesis; Oxazines - pharmacology; Phthalimides - chemical synthesis; Phthalimides - pharmacology; Physical Sciences; phytotoxicity; Plants - drug effects; quantitative structure-activity relationships; Science & Technology; Structure-Activity Relationship; synthesis; weed control; Zea mays; synthesis; Digitaria sanguinalis; PHYTOTOXICITIES; herbicidal activity; PROTOPORPHYRINOGEN; benzo[b][1,4]oxazin-6-yl-isoindoline-1,3-dione; protox inhibitor; Abutilon theophrasti Medic; Malvaceae; Abutilon theophrasti; Monocotyledones; Synthesis; Gramineae; Dicotyledones; Angiospermae; Spermatophyta; Inhibitor; Benzo[b][1,4]oxazin-6-yl-isoindoline-1,3-dione
• DOI: 10.1021/jf051494s
• ISSN: 0021-8561

The mode of action of 2-(7-fluoro-3-oxo-3,4-dihydro-2H-benzo[b][1,4]oxazin-6-yl)-4,5,6,7-tetrahydro-2H-isoindoline-1,3-diones, including the commercial herbicide flumioxazin, had been identified as inhibition of protoporphyrinogen oxidase (protox). As part of continuous efforts to search for new herbicides with high efficacy, broad-spectrum activity, and safety to crops, flumioxazin and its iodo analogue (B2055) were used as lead compounds for further optimization. Series of novel compounds were prepared by multistep synthetic procedures starting from 5-fluoro-2-nitrophenol. All of the test compounds were structurally confirmed by 1H NMR, IR, mass spectroscopy, and elemental analysis. Preliminary bioassay data showed that some of them possess commercial levels of herbicidal activity comparable to those of other protox-inhibiting herbicides. One of the best compounds, 5-fluoro-2-(7-fluoro-3-oxo-4-(prop-2-ynyl)-3,4-dihydro-2H-benzo[b][1,4]oxazin-6-yl)isoindoline-1,3-dione (8e), has IC50 values for velvetleaf (Abutilon theophrasti Medic) and crabgrass (Digitaria sanguinalis) comparable to thos of B2055. With respect to crop selectivity, compound 8e is similar to flumioxazin. Compound 8e is safe to cotton and maize at a rate of 150 g of active ingredient (ai)/ha or less when applied at pre-emergent stage, and it has the best safety to wheat among the tested crops, showing no injury after post-emergent application at 7.5−30 g of ai/ha. Keywords: Benzo[b][1,4]oxazin-6-yl-isoindoline-1,3-dione; protox inhibitor; synthesis; herbicidal activity; Digitaria sanguinalis; Abutilon theophrasti Medic