Urea derivatives containing a heterocyclic group

Of the 1,3,4-thiadiazole derivatives already approved for agricultural use, tebuthiuron, l-(5-/-butyl-l,3,4-thiadiazol-2-yl)-l,3-dimethylurea (37) thiaza-fluron, 1,3-dimethyl-l-(5-trifluoromethyl-l,3,4-thiadiazol-2-yl)urea (38) and sul- 

Of the urea derivatives containing the benzothiazolyl group as substituent two compounds are used in agriculture benzthiazuron, I-(benzothiazol-2-yl)-3-methylurea (43) (Hack et ai, 1966) and methabenzthiazuron, l-(benzothiazol-2-yl)-3,3-dimethylurea (44) (Searle, 1956 Hack et al, 1967 Hack, 1968). The former is selective in sugar beet and spinach, the latter in cereals, pea, bean and other crops. 

Benzthiazuron and methabenthiazuron are prepared by the condensation of 2-aminobenzothiazole and 2-methylaminobenzothiazole, respectively, with methyl isocyanate (Hack et al., 1966, 1967)  

Tebuthiuron (37) was developed by the Elanco Prod. Co., in the period 1972-1974 (Schwer, 1974). 

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