Improvement of synthesis method of 6-methoxyisatin

Objective To improve the synthetic condition of 6-methoxyisatin.Methods The starting material 3-methoxyaniline was firstly converted into the intermediate 1-oximino-N-(3-methoxyphenyl)acetamide through Sandmeyer reaction,then 6-methoxyisatin was conducted with methanesulfonic acid as catalyst in the following ring closure reaction.ResultsIn 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%.ConclusionThis 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.