1.2 g Ethyl 3-(4-aminomethylbenzoylamino)propanoate hydrochloride (4.18 mmol) was mixed with 20 mL 1,2-dichloroethane and 6 mL saturated K2CO3 by vigorous stirring. The phases were separated and the aqueous phase was extracted with another 20 mL 1,2-dichloroethane. 240 μL HOAc was added to the combined 1,2-dichloroethane phase followed by 0.691 g 1,4-dioxaspiro[4.5]decan-8-one (4.42 mmol). 1.272 g NaBH(OAc)3 (6 mmol) was added and the reaction was stirred for 16 hours at 25° C. The reaction volume was reduced on a rotary evaporator to about 20 mL and then poured into a mixture of 60 mL H2O and 10 mL sat. K2CO3. The phases were separated and the aqueous phase was extracted twice with 40 mL 1,2-dichloroethane. The combined 1,2-dichloroethane fractions were dried over MgSO4 and evaporated to afford the title compound. The crude product was used in the next step without further purification.
