Sulfonylaminocarbonyl-triazolinones

The first examples of the new herbicidal dass of sulfonylaminocarbonyl-triazolinones (SACTs) were reported in 1989 [1]. Following intensive chemical optimization two representatives were developed and commerdalized for selective weed control in cereals. In 2000, flucarbazone-sodium (1) was introduced in the Canadian market under the trade name Everest for the control of wild oats Avenafatua) and green foxtail Setaria viridis) in spring wheat Triticum aestivum) and durum wheat (Triticum durum) (Fig. 2.6.1). 

Both compounds are inhibitors of the acetolactate synthase enzyme, also known as aceto hydroxy acid synthase (AHAS) and are classified in group B by the Herbicide Resistance Action Committee HRAC. Table 2.6.1 gives the physicochemical properties of 1 and 2. 

The discovery of the herbicidal class of SACTs is outlined in detail in Ref. [2]. Starting from the concept of seeking new applications for the Nylon 6 intermedi- 

Amongst many other derivatives (by NH-acylation, sulfonylation, alkylation, arylation) a sulfonylaminocarbonyl-triazolinone with the internal code no. BAY DAM 4493 was synthesized in 1985 (Fig. 2.6.3). It showed not only activity against rice blast Pyricularia oryzae) but also phytotoxic symptoms at application rates of 500 g a.i. ha h 

About two years later this compound was identified in an in vitro assay as an unusual ALS inhibitor [4-6] and was the starting signal for a major synthesis program. 

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With the invention of the aceto-hydoxy-add synthesis inhibitors (AHAS) the dominance of herbiddes that ad as photosynthesis inhibitors was dramatically broken - as it was also by the development of genetically modified herbicide tolerant crops. These especially important areas of research and development, from the 1990s up to now, are exemplified in Chapters 3 and 7. The development of 12 new sulfonyl urea herbicides launched since 1995 and the invention of four development compounds of the same chemical class, after the introduction to the market of twenty compounds already between 1980 and 1995, refleds the importance of this biochemical mode of adion for the herbicide market as well as the different chemistries found to be active at this target, such as imidazolinones, triazolo-pyrimidines, pyrimidinyl-carboxylates, and sulfonylaminocarbonyl-triazolinones. 

D. Bielefeldt, M. Dollinger, H.-J. Santel, K. Stenzel, 1996, Herbiddal or fungicidal sulfonylaminocarbonyl-triazolinones with halogenated alk(en)ylthio substituents, WO 1996/ 27591 (Prio 08. 03. 1995), Bayer AG, Leverkusen, Germany. 

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