13122-90-2

13122-89-9

13122-90-2

General procedure for the synthesis of Boc-L-phenylalanyl-phenylalanine from methyl (tert-butoxycarbonyl)phenylpropionyl-phenylpropionate: to a solution of methanol (20 ml) containing methyl 2-(2-((tert-butoxycarbonyl)amino)-3-phenylpropionamido)-3-phenylpropionate (2.0 g, 4.69 mmol), sodium hydroxide (0.38 g, 9.38 mmol) in water (10 ml) solution and the reaction temperature was maintained at 25-30°C. The reaction mixture was stirred at the same temperature for 1 hour. After completion of the reaction, methanol was removed by evaporation and the remaining aqueous layer was acidified with citric acid solution until the solid precipitated. The solid product was collected by filtration and dried to give Boc-L-phenylalanyl-phenylalanine as a white solid (1.89 g, 98% yield); ESI-MS: 413.2 (M + H).