A mixture of 0.7 g of diphenylmethyl 3-[4-(2-azidoethyl)-2,3-dioxopiperazin-1-yl]-3-(pyridin-3-yl)-propionate, 0.13 g of 5% palladium-carbon, 2.8 ml of 1N hydrochloric acid and 7 ml of N,N-dimethylformamide was subjected to hydrogenation at ordinary temperature and atmospheric pressure for 2 hours. After completion of the reaction, the catalyst was filtered off and the filtrate was concentrated under reduced pressure. To the resulting residue were added 5 ml of diethyl ether and 1 ml of ethyl acetate and the resulting mixture was filtered to obtain a white solid. The solid obtained was added to a mixed solvent of 20 ml of methylene chloride and 10 ml of a saturated aqueous sodium hydrogencarbonate solution and stirred for 10 minutes. The organic layer was separated and the aqueous layer was extracted with two 10-ml portions of methylene chloride. The combined organic layer was washed with water and then a saturated aqueous sodium chloride solution. After drying over anhydrous magnesium sulfate, the solvent was distilled off under reduced pressure to obtain 0.2 g of diphenylmethyl 3-[4-(2-aminoethyl)-2,3-dioxopiperazin-1-yl]-3-(pyridin-3-yl)-propionate as a brown oil.
