Triethylamine → 2,6-Bis-(2-benzyloxy-acetylamino)-hexanoic acid methyl ester

To a mixture of L-lysine methyl ester dihydrochloride (50 grams, 214.4 mmol), triethylamine (131 grams, 1.294 moles) in ethyl acetate (750 mL) at room temperature was added benzyloxy acetyl chloride (120 grams, 650.4 mmol) drop wise. The mixture was further stirred at room temperature for 2 hours. The solids were filtered off. The organic phase was washed with 5% sodium bicarbonate (2×100 mL), water (2×100 mL), dried over sodium sulphate and distilled. The crude 2 was purified by column chromatography on silica gel using Benzene: Ethyl acetate (9:1) to get pure 2 (30 grams, 31.8%) as a white powder.