N-(1-Octyl-5-ethoxycarbonylmethyl-4,6-dimethylindol-7-yl)-2,2-dimethylpropanamide (3.5 g) was dissolved in EtOH (50 ml), and a solution of NaOH (1.6 g) in water (20 ml) was added, which was followed by stirring at 60° C. for 1 hr. EtOH was evaporated under reduced pressure, and the residue was dissolved in water (20 ml), and washed with AcOEt (10 ml). The aqueous layer was neutralized with 2N HCl and extracted with AcOEt (50 ml). The AcOEt layer was washed successively with saturated brine and dried over anhydrous sodium sulfate. AcOEt was evaporated under reduced pressure to give 2.0 g of the title compound.
