| 摘要 |
<p>A process for preparing an alkyl α-2-chloro-5- [4-(difluoromethyl)-4,5- dihydro-3-methyl-5- oxo-1H-1,2,4-triazol -1-yl]-2,4-substituted -benzene-propanoate herbicide, by reacting an alkyl α-acetyl-5- [4-(difluoromethyl)-4,5- dihydro-3-methyl-5- oxo-1H-1,2,4-triazol -1-yl]-2,4-disubstituted -benzene-propanoate, Intermediate D, first with sodium hypochlorite, then with a base, and recovering the herbicide. Intermediate D is prepared by reacting a 1-(2,4-disubstituted-5- halophenyl)-4-difluoromethyl-4, 5-dihydro-3-methyl-5- oxo-1H-1,2,4-triazole, Intermediate B, with an alkyl alkanoate in the presence of a palladium catalyst and a tertiary amine. Intermediate B is prepared by reacting a 1-(2,4-disubstituted- phenyl)-4-difluoromethyl-4, 5-dihydro-3-methyl-5- oxo-1H-1,2,4-triazole with a halogenating agent in the presence of an acid. The 2,4-substituents are independently selected from halo, alkyl, cycloalkyl, alkoxy, nitro, or hetercyclyl.</p> |
