General Procedure G. N-Boc Protection. The corresponding amine (1 equiv) was dissolved in H2O (5 mL/mmol). NaHCO3 (1.1 equiv) and a solution of Boc2O (1.6 equiv) in EtOAc and H2O (1:1) were added to the mixture at 0°C. After stirring for 2 h at 0°C, the phases were separated, and the organic phase was washed with saturated aqueous NaHCO3 (25 mL/mmol) and brine (25 mL/mmol), dried over Na2SO4, filtered and concentrated in vacuo. The product was used in the next step without further purification. (1). This compound was synthesized as described previously.