Under ice cooling, 1.10 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride was added to a stirred mixture of 1.22 g of 3-amino-2,3-dihydro-1-pentyl-1H-indol-2-one hydrochloride, 0.93 g of 1,2,3,4-tetrahydronaphthalene-2-carboxylic acid, 0.72 g of 1-hydroxybenzotriazole and 40 ml of methylene chloride. After the reaction mixture was stirred under ice cooling for 1 hour, 1.0 ml of triethylamine was added to the mixture. The resulting mixture was stirred under ice cooling for 2 hours and then stirred at room temperature for 2 hours. The solvent was removed by evaporation under reduced pressure. The residue was extracted with ethyl acetate, and the extract was washed and dried. After removal of solvent, the residual solid was recrystallized from ethyl acetate-hexane to afford 1.36 g of N-(2,3-dihydro-2-oxo-1-pentyl-1H-indol-3-yl)-1,2,3,4-tetrahydronaphthalene-2-carboxamide as colorless crystals. Melting point: 127° to 132° C., IR (Nujol) (cm-1): 3280, 1725, 1640, 1610, MS (m/z): 376 (M+), 218 (base), 147, 31.
