Patent ID: 6077959
Filing Date: 2000-06-20
Classification: C07D

Abstract:
A process for preparing ethyl .alpha.-2-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2 ,4-triazol-1-yl]-4-fluorobenzenepropanoate, comprising reacting ethyl .alpha.-acetyl-2-chloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1 H-1,2,4-triazol-1-yl]-4-fluorobenzenepropanoate (""Intermediate D""), first with sodium hypochlorite, then with a base, recovering the Herbicide, said Intermediate D being prepared by reacting 1-(4-chloro-2-fluoro-5-bromo or 5-iodophenyl)-4-difluoromethyl-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol e (""Intermediate B""), with ethyl 3-hydroxy-2-methylenebutanoate or ethyl acrylate in the presence of a palladium catalyst and a tertiary amine, said Intermediate B being prepared by reacting 1-(4-chloro-2-fluorophenyl)-4-difluoromethyl-4,5-dihydro-3-methyl-5-oxo-1H -1,2,4-triazole with a brominating or iodinating agent in the presence of an acid.