4种氮杂双环化合物的合成方法改进

Modified Synthesis of Four Kinds of Azabicyclo Compounds

以邻苯二胺及2,3-二氨基吡啶为原料,与羰基化合物反应制备苯并吡嗪、吡啶并吡嗪、苯并咪唑和吡啶并咪唑4种氮杂双环化合物,探讨了溶剂、温度、时间和pH值等实验条件对反应的影响。在合成吡啶并吡嗪时,采用正丙醇为溶剂,用甲醇钠调节pH=9,回流反应1 h,将收率从35.7%提高至89.4%;在合成苯并吡嗪时,用水作溶剂,用亚硫酸钠调节pH=9,60℃反应40 min,产物纯化采用低温静置代替减压蒸馏,收率可提高至98.3%;尝试不同方法合成苯并咪唑和吡啶并咪唑,确定最优合成条件分别为:邻苯二胺在88%的甲酸溶液中回流2 h,苯并咪唑收率为92%;2,3-二氨基吡啶在原甲酸三已酯中回流3 h,加浓盐酸继续回流1 h,吡啶并咪唑收率为84.2%。

Azabicyclo compounds of 1,4-benxodiazine,pyridopyrazine,1H-benzimidazole,3H-imidazopyridine were prepared from o-phenylenediamine or 2,3-diaminopyridine reacted with carbonyl compounds.The effects of reaction medium,pH,time and other factors on the reactions were invesitigated.The results showed that the yield of pyridopyrazine could reach 89.4% when refluxed in propanol for 1 h at pH=9 adjusted by methanol sodium.The yields for 1,4-benxodiazine could be increased to 98.3% in aqueous medium with pH=9 adjusted by sodium sulfite at 60 ℃ after 40 min reaction.Here,the purification of target product could be achieved via a low temperature standing process instead of the vacuum distillation method.The optimized conditions for the other two compounds are： refluxing o-phenylenediamine for 2 h in 88% formic acid solution yielding 1H-benzimidazole with 92% yield;refluxing 2,3-diaminopyridine with triethoxy methane for 3 h followed by adding concentrated hydrochloric acid for another 1 h giving 3H-imidazopyridine with 84.2% yield.