The general procedure for the synthesis of diethyl 1-(2,4-dichlorophenyl)-5-methyl-4,5-dihydro-1H-pyrazole-3,5-dicarboxylate from ethyl methacrylate and ethyl 2-chloro-2-(2-(2,4-dichlorophenyl)hydrazinylidene)acetate was as follows: 22.8 g of ethyl methacrylate and 14.8 g of 2-chloro-2-(2-(2,4-dichlorophenyl) hydrazinyl) ethyl acetate were mixed and heated to 50-60 °C. Over 30 minutes, 7.6 g of triethylamine was slowly added dropwise to the reaction mixture. Subsequently, the reaction temperature was raised to 70 °C and the reaction was continued with stirring for 2 hours. After completion of the reaction, the reaction mixture was allowed to cool to room temperature and the precipitate was isolated by filtration. The filtrate was carefully concentrated under reduced pressure to afford 18.1 g of the target product 1-(2,4-dichlorophenyl)-5-methyl-4,5-dihydro-1H-pyrazole-3,5-dicarboxylic acid diethyl ester.
![ethyl chloro[(2,4-dichlorophenyl)hydrazono]acetate](/CAS/20180711/GIF/27143-12-0.gif)
