非均相条件下苯并吡唑衍生物的合成

Synthesis of Benzopyrazole Derivatives Under Heterogenous Condition

苯并吡唑衍生物是重要的有机合成中间体,具有良好的药物活性.在乙酸乙酯和50%(质量分数)硫酸水溶液(体积比1∶1)的两相混合溶剂中,邻氨基苯乙腈或邻氨基苯乙酰胺与重氮化试剂亚硝酸钠在55℃下搅拌5 min,以高产率(83%~98%)转化为一系列苯并吡唑衍生物.考察了不同的酸、酸的质量分数及用量、不同有机溶剂对反应的影响,确定了最优反应条件.此外,还提出了可能的反应机理,认为重氮盐是该反应的关键中间体.该反应具有操作简单、原料廉价易得、反应条件温和、反应迅速、产率高等优点,为苯并吡唑衍生物的合成提供了一种高效的新方法.

Benzopyrazole derivatives are important intermediates in organic synthesis with good pharmaceutical activities.In the two-phase mixed solvent of ethyl acetate and 50%(mass fraction)sulfuric acid solution(volume ratio 1∶1),ortho-aminobenzacetonitriles or ortho-aminobenzacetamide and diazotization reagent sodium nitrite were stirred at 55℃for 5 min,and a series of benzopyrazole derivatives were converted in high yields(83%~98%).The effects of different acids,acid concentrations and dosages of acid and different organic solvents on the reaction were investigated to determine the most suitable reaction conditions.In addition,a possible reaction mechanism was proposed,in which diazonium salt is proposed to be the key intermediate.The reaction has the advantages of simple operation,cheap and readily available to obtain raw materials,mild reaction conditions,rapid reaction and high yield,which provides a new and efficient method for the synthesis of benzopyrazole derivatives.