Résumé
Objective To improve the synthetic condition of 6‐methoxyisatin .Methods The starting material 3‐me‐thoxyaniline was firstly converted into the intermediate 1‐oximino‐N‐ (3‐methoxyphenyl) acetamide through Sandmeyer reac‐tion ,then 6‐methoxyisatin was conducted with methanesulfonic acid as catalyst in the following ring closure reaction .Results In the second step of the cyclization reaction ,methanesulfonic acid was used to replace the concentrated sulfuric acid which is widely used in literature .The temperature was 80℃ ,the reaction time was 30 min ,and the yield was 81.24% .Conclusion This study provided a synthesis process of 6‐methoxyisatin with simple operation ,mild reaction condition and high yield ,which is suitable for large scale preparation of the compound .