FS-205-397 can be obtained by two related ways: 1) The acetylation of 6-ethoxyindolin-2-one (I) with refluxing acetic anhydride gives 1-acetyl-6-ethoxyindolin-2-one (II), which is methylated with methyliodide and butyllithium in HMPT to yield 6-ethoxy-3,3-dimethylindolin-2-one (III). Finally, this compound is reduced with LiAlH4 in THF. 2) The acetylation of 6-hydroxyindolin-2-one (IV) with refluxing acetic anhydride gives 6-acetoxy-1-acetylindolin-2-one (V), which is methylated as before, affording 6-hydroxy-3,3-dimethylindolin-2-one (VI). Finally, this compound is ethylated with ethyl iodide and K2CO3 in refluxing acetone to give the indolinone (III), already obtained.

FS-205-397 can be obtained by two related ways: 1) The acetylation of 6-ethoxyindolin-2-one (I) with refluxing acetic anhydride gives 1-acetyl-6-ethoxyindolin-2-one (II), which is methylated with methyliodide and butyllithium in HMPT to yield 6-ethoxy-3,3-dimethylindolin-2-one (III). Finally, this compound is reduced with LiAlH4 in THF. 2) The acetylation of 6-hydroxyindolin-2-one (IV) with refluxing acetic anhydride gives 6-acetoxy-1-acetylindolin-2-one (V), which is methylated as before, affording 6-hydroxy-3,3-dimethylindolin-2-one (VI). Finally, this compound is ethylated with ethyl iodide and K2CO3 in refluxing acetone to give the indolinone (III), already obtained.