Benzoates herbicidal activity

This paper traces in some detail the path which led to the discovery of a new class of herbicides, the 2-(5-oxo-2-imidazolin-2-yl)arylcarboxylates. The journey started when it was found that a phthalimide, a-isopropyl-a-methyl-l,3-dioxo-2-isoindoline-acetamide, had sufficient herbicidal activity to warrant further synthesis effort. This work led to a series of analogs essentially devoid of herbicidal activity yet possessing interesting plant growth regulating effects. Further chemical modifications resulted in the synthesis of two new groups of compounds, imidazoisoindolediones and dihydro-imidazoisoindolediones, and the return of herbicidal activity. The imidazoisoindolediones were in turn transformed into o-(5-oxo-imidazo-lin-2-yl)benzoates, the first members of a very interesting new class of herbicides. 

Herbicidal Activity of Various Benzoate Derivatives Control Rates in Kg/Ha... 

Although the ALS inhibitor herbicides have been used for approximately 20 years, the number of resistant weed biotypes for this group now exceeds those for all other types of herbicides. Singh and Shaner (1995) and Boutsalis (2001) reported that a total of five chemical families or herbicide classes are commercially marketed as inhibitors of ALS, and that these herbicides comprise more than 50 active ingredients for selective use in many different crops. They include sulfonylureas, imidazolinones, triazolopyrimidines, sulfonylamino-carbonyl-triazolinones, and pyrimidinyl (thio)benzoates. 

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