Sodium hydride → N-ethoxycarbonylpentyl-N-phenylamine

Under ice-cooling, 1.87 g of 62% sodium hydride was added to 100 ml of a dimethylformamide (DMF) solution containing 10.00 g of N-benzyloxycarbonylaniline, and the mixture was stirred at room temperature for one hour. Under ice-cooling, to the above mixture was added dropwise 50 ml of a DMF solution containing 10.31 g of ethyl 6-bromohexanoate, and the resulting mixture was stirred at room temperature overnight. DMF was removed under reduced pressure and water was added to the residue. The mixture was extracted with ethyl acetate. The extract was washed and dried, and the solvent was removed under reduced pressure. The residue was dissolved in 160 ml of methanol and 2 g of 10% palladium-carbon (Pd-C) was added to the solution. The mixture was subjected to catalytic reduction at normal temperature under normal pressure for 2 hours. After removing the catalyst by filtration, the filtrate was condensed and the residue was purified by silica gel column chromatography (solvent; hexane:ethyl acetate=4:1) to give 8.13 g of N-ethoxycarbonylpentyl-N-phenylamine (yield; 79%, melting point: 34°-37° C.).