合成路线1

The reduction of 4,6-dimethylindole (I) with NaBH3CN in AcOH produced indoline (II), which was acetylated with Ac2O to give amide (III). Introduction of a blocking group at position 5 of (III) was effected by bromination in AcOH, yielding (IV). Then, nitration of (IV) with HNO3/H2SO4 furnished the 7-nitroindoline (V). After basic hydrolysis of the acetamide group of (V), the resulting indoline (VI) was N-alkylated with n-pentyl bromide (VII) and NaH to afford (VIII). Reduction of the nitro group of (VIII) with simultaneous hydrogenolysis of the bromine atom was carried out by hydrogenation over Pd/C to produce amino indoline (IX). Finally, the title amide was obtained by coupling of (IX) with pivaloyl chloride in the presence of Et3N.