2-氨基-1H-苯并[d]咪唑-5-羧酸的合成

Synthesis of 2-Amino-1H-benzo[d]imidazole-5-carboxylic Acid

3,4-二氨基苯甲酸甲酯(化合物1)与溴化氰反应得到2-氨基-1H-苯并[d]咪唑-5-羧酸甲酯(化合物2),之后在碱性条件下水解得到目标化合物2-氨基-1H-苯并[d]咪唑-5-羧酸(化合物3),其结构经1H NMR、13CNMR和MS确证,并对中间体2的合成条件进行优化:物料比n(化合物1)∶n(溴化氰)=1∶3,反应溶剂为甲醇与水的1∶1混合溶液,反应温度为50℃,反应时间为2 h。在上述条件下,化合物2收率达到97%,目标化合物的总收率为90%。该方法为苯并咪唑衍生物的合成提供了参考。

2-Amino-1 H-benzo[d]imidazole-5-carboxylic acid methyl ester(compound 2) was synthesized by the reaction of methyl 3,4-diaminobenzoate(compound 1) with cyanogen bromide. Then, the target compound 2-amino-1 H-benzo[d]imidazole-5-carboxylic acid(compound 3) was obtained by hydrolysis under alkaline conditions, and its structure was confirmed by 1 H NMR, 13 C NMR and MS, and the synthesis conditions of intermediate 2 were optimized: the material ratio n(compound 1)∶n(cyanogen bromide) =1∶3, The reaction solvent was methanol and water mixed solution with the volume ratio of 1∶1, and the reaction temperature was 50 ℃,the reaction time was 2 h. Under these conditions, the yield of compound 2 reached 97%, and the total yield of the target compound was 90%. This method provides some reference for the synthesis of benzimidazole derivatives.