超声辅助2-取代硫醚-5--1,3,4-噁二唑类化合物的合成

Ultrasound-Assisted Synthesis of 2-Substituted Thioether-5-[5-(4-nitrophenyl)-1 H-pyrazole-3-yl]-1,3,4-oxadiazole Compounds

以5-(4-硝基苯基)-1 H-吡唑-3-甲酸乙酯(1)为起始原料,经肼解和关环合成了中间体5-[5-(4-硝基苯基)-1 H-吡唑-3-基]-2-巯基-1,3,4-噁二唑(3)。在超声作用下,以乙腈为溶剂,固体K2CO3为缚酸剂,使化合物3与卤代烃反应合成4个含取代吡唑基的1,3,4-噁二唑硫醚类化合物4a～4d,该法具有反应时间短、产率较高和操作简便等特点。产物结构经元素分析、IR、1 H NMR表征。

5-[5-(4-nitrophenyl)-1 H-pyrazole-3-yl]-2-mercapto-1,3,4-oxadiazole (3) was obtained from ethyl 5-(4-nitrophenyl)-1 H-pyrazole-3-carboxylate (1) through the hydrazinolysis and cyclization.Four 2- substituted thioether-5-[ 5-(4-nitrophenyl)-1 H-pyrazole-3-yl]-1,3,4-oxadiazole compounds 4a^4d were then synthesized by the reaction of 3 and alkyl halides using potassium carbonate as acid-accepter in acetonitrile uunder ultrasound irradiation.This method is of the advantages of good yields,short reaction time and easy operation.The structures of products were characterized by IR,^1 H NMR and elemental analyses.