Synthesis of starting materials (Benzyloxy)glycine(Benzyloxy)glycine was prepared according to a modified literature procedure. 1 To a solution of 3.09 g (17.3 mmol, 1.0 eq.) 2-((Benzyloxy)imino)acetic acid 1 in 32 mL ethanol were added 12.0 mL (ρ = 0.777 g/mL) borane triethylamine complex at 0 °C. 58.4 mL 10 % aqueous HCl were added dropwise over 15 min. After completion of the addition, the mixture was warmed to room temperature and stirred for 2 h. The solution was washed with CHCl3 (organic layer discarded) and adjusted to pH = 3-4 by the addition of 1 M NaOH at 0 °C, resulting in precipitation of a solid. The mixture was extracted with CH2Cl2 three times and the organic layers were dried over Na2SO4 and concentrated in vacuo. Crude (benzyloxy)glycine was obtained in 58 % yield (1.81 g, 9.99 mmol) as a colorless solid, HPLC: tR = 0.66 min; and used in the next step without further purification. Analytical data were in accordance with those previously reported. 1Note: The crude product can be purified by recrystallization from water, but with considerable product loss. It is therefore recommended to directly use the crude product in the next step.