N-(5-Ethoxycarbonylmethyl-4,6-dimethylindol-7-yl)-2,2-dimethylpropanamide (1.45 g) was dissolved in DMF (10 ml) and NaH (P=60%, 132 mg) was added under a nitrogen atmosphere, which was followed by stirring at room temperature for 1 hr. Then, 1-iodooctane (1.06 g) was added and the mixture was stirred at the same temperature for 2 hr. The reaction mixture was poured into ice water. The mixture was extracted with AcOEt (100 ml), washed with water and dried over anhydrous sodium sulfate. AcOEt was evaporated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: benzene/AcOEt=1/0−1/1) to give 1.02 g of N-(1-octyl-5-ethoxycarbonylmethyl-4,6-dimethylindol-7-yl)-2,2-dimethylpropanamide.
