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以3-氨基吡啶为原料,经取代、重氮化得到2,3-二氯吡啶,再与水合肼经亲电取代制得3-氯-2-肼基吡啶。所得产品无需提纯可直接用于下一步反应。所得产物与马来酸二乙酯在氮气保护条件下,以无水乙醇为溶剂,反应得到有机中间体2-(3-氯-2-吡啶基)-5-氧代-3-吡唑烷甲酸乙酯,反应总产率为48.0%。所得产物经IR、1HNMR确定其结构。并对合成工艺进行优化,所得适宜工艺条件(以3-氯-2-肼基吡啶228.57 mmol计):在无水无氧反应体系中,回流状态下滴加马来酸二乙酯速度为10 s/滴时,回流反应1 h,产率为80.1%。
Using 3-aminopyridine as raw material, 2,3-dichloropyridine was obtained by substitution and diazotization, and 3-chloro-2-hydrazinopyridine was obtained by electrophilic substitution with hydrazine hydrate. The resulting product can be directly used for the next reaction without purification. The resulting product was reacted with diethyl maleate in anhydrous ethanol under a nitrogen atmosphere to give the organic intermediate 2- (3-chloro-2-pyridyl) -5-oxo-3-pyrazolidine Ethyl formate, the overall reaction rate was 48.0%. The product was confirmed by IR, 1HNMR structure. And the synthesis process was optimized, the appropriate process conditions (with 3-chloro-2-hydrazinopyridine 228.57 mmol): In anhydrous anaerobic reaction system, diethyl maleate was added dropwise at reflux rate of 10 s / drop, the reaction was refluxed 1 h, the yield was 80.1%.