| 摘要 |
NEW MATERIAL:The pyrazole derivative of formula I (A is lower alkyl; R<1> is H or lower alkyl; R<2> is lower alkyl or benzyl). EXAMPLE:Ethyl 5-benzylthio-1-methylpyrazole-4-carboxylate. USE:Intermediate of pharmaceuticals and agricultural chemicals, etc. such as herbicides. PREPARATION:The objective compound of formula I can be prepared by reacting the formylacetic acid derivative of formula II with the dithiocarbazinic acid derivative of formula III in an inert solvent such as tetrahydrofuran, usually at -20-+80 deg.C. The compound of formula IV is obtained from the compound of formula I in shorter steps than the conventional process, easily and economically in an industrial scale, without producing isomers nor necessitating the disposal of waste products, by oxidizing the compound of formula I with chlorine, and treating the product with ammonia water. A high-quality herbicide can be prepared from the compound of formula IV in a short step in high yield.
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