General procedure for the synthesis of methyl 3-amino-3-(4-nitrophenyl)propionate from methanol and 3-amino-3-(4-nitrophenyl)propionic acid: 3-amino-3-(4-nitrophenyl)propionic acid (5 g, 23.8 mmol) was added to a solution of methanol (125 ml) containing acetyl chloride (5 ml). The reaction mixture was stirred at room temperature overnight. After completion of the reaction, the solvent was removed by distillation under reduced pressure. The resulting solid was ground with hot ether and subsequently collected by filtration and washed with ether to give methyl 3-amino-3-(4-nitrophenyl)propionate as a light yellow powder (5.35 g, 100%). δH(D2O) 8.32 (2H, d, J=8.9 Hz, ArH), 8.75 (2H, d, J=8.9 Hz, ArH), 4.90 (1H, dd. J=7.2,6.9Hz, CHNH2), 3.70 (3H, s, CO2Me), 3.19 (1H, dd, J=17.1,7.5Hz, CHAHB), and 3.09 (1H, dd, J=17.1,6.6Hz, CHAHB); m/z (ES+, 60V) 225 (MH+).
