1,4-oxathiin fungicides

Oxathiine derivatives lb 301,304 Oxathizine fungicides la 44 Oxazepam la 364 Oxazolidinthione derivatives lb 301 Oxeladine citrate lb 327 Oxidation, aluminium isopropoxide la 59 -, atmospheric oxygen la 60 -, chromic acid la 59, 60 -, hydrogen peroxide la 59 -, iodine la 60... 

Derivatives of 2,3-dihydro-l,4-oxathiin and 1,4-benzoxathiins have been patented as agrochemicals. An important development in fungicidal research has been the discovery of so-called systemic fungicides. Unlike surface fungicides which may require repeated... 

Farrow et al. [159] determined the systemic fungicide carboxin (2,3-dihy-dro-6-methyl-5-phenylcarbamoyl-l,4-oxathiin), which is used in barley and wheat seed treatment of cereals. 

Mathre, D.E. (1971) Mode of action of oxathiin systemic fungicides. Structure-activity relations. J. Agric. Food Chem. 19(5), 872-874. McCall, P.J., Swann, R.L., Laskowski, D.A., Unger, S.M., Vrona, S.A., Dishburger, H.J. (1980) Estimation of chemical mobility in soil from liquid chromatographic retention times. Bull. Environ. Contam. Toxicol. 24, 190-195. 

Obviously, one can not precisely quantify the elements of Figure 8. It is nevertheless highly indicative. Resistance of a practical nature is rarely, if ever, encountered in normal field practice by the sulfenimides (or for example, the dithio-carbamates, Figure 9) - insoluble, multisite protectives. The water soluble single site and variably translocatable antibiotics, benzimidazoles, oxathiins, etc., etc., all exhibit degrees of field resistance. As far as this author knows, this analysis can be extended over the whole class of plant protection fungicides. 

Uses fungicide, cereals, ornamentals Trade names Plantvax (Uniroyal) Type oxathiin, amide, sulfone... 

It was not until the late 1960s that effective systemic fungicides appeared on the market, and their development represents an important breakthrough in the field of plant chemotherapy. The major classes of systemic fungicides developed since 1966 are oxathiins, benzimidazoles, thiophanates, and pyrimidines. Other effective systemic fungicides used currently include antibiotics, morpholines, organophosphorus compounds, and most recently, the sterol biosynthesis inhibitors, e.g., triazoles. 

Fungicides of carboxamide type became known in 1966 with the discovery of carboxin (which has an oxathiin skeleton), which began a new chapter in the chemotherapy of plant diseases. This group actually has a much longer history —... 

The most widely used fungicide of the carboxamide group, carboxin (9), contains an oxathiin ring. Its composition is 5,6-dihydro-2-methyl-l,4-oxathiin-3-carboxanilide (Von Schmeling and Kulka, 1966). Its synthesis starts with acetoacetanilide (7), which with sulfuryl chloride gives 2-chloro-3-oxobutyranilide... 

Dihydro-2-methyl-l,4-oxathiin-3-carboxanilide (92), known as Carboxin (a fungicide), rearranges to the enamine (93) when refluxed in toluene with / -toluenesulfonic acid. The structural assignment of (93) are made on the basis of crystal x-ray diffraction analysis <84MI 609-02>. 

Oxathiins. Carboxin and Oxycarboxin, introduced in 1966, were the first commercially successful systemic fungicides. They are selectively toxic to a number of cereal diseases such as smuts and rust. Again the mode of action involves enzyme inhibition. 

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