A solution of 3.55 g of ethyl 3-amino-4,4,4-trifluorocrotonate in 50 ml of n-hexane is added dropwise with stirring and at 0°-3° C. during 15 minutes to 0.85 g of a 55% sodium hydride dispersion in 50 ml of dimethylformamide, and the mixture is stirred for a further 30 minutes. Then a solution of 5.0 g of isopropyl 2-chloro-4-fluoro-5-isocyanatobenzoate in 100 ml of n-hexane is added dropwise during 5 minutes with stirring and cooling. The temperature of the reaction mixture rises to 10° C., and the mixture is thereafter stirred for one hour at room temperature. The isopropyl 2-chloro-4-fluoro-5-{3-[2-(ethoxycarbonyl)-1-trifluoromethyl-vinyl]ureido}benzoate which is formed as an intermediate is not isolated.
