67630-00-6

67630-01-7

The general procedure for the synthesis of ethyl (S)-3-(4-aminophenyl)-2-((tert-butoxycarbonyl)amino)propionate from ethyl (S)-2-((tert-butoxycarbonyl)amino)propionate was as follows: first, ethyl N-BOC-4-nitro-L-phenylalaninate (78.3 g, 0.22 mol) was dissolved in anhydrous ethanol ( 300 mL) and the solution was purged with nitrogen to remove oxygen. Subsequently, 10% palladium carbon catalyst (1.0 g) was added. The hydrogenation reaction was carried out under hydrogen pressure of 40-50 psi for 1 hour. Upon completion of the reaction, the reaction mixture was filtered through diatomaceous earth to remove the catalyst. The filter cake was washed sequentially with ethanol (EtOH) and ethyl acetate (EtOAc). The filtrates were combined and concentrated to obtain the crude product. Finally, the residue was purified by silica gel fast column chromatography with an eluent ratio of 4:1 to 1:1 ethyl acetate/hexane to afford the target product ethyl (S)-3-(4-aminophenyl)-2-((tert-butoxycarbonyl)amino)propanoate (60 g, 89% yield). The product was characterized by 1H NMR (400 MHz, CDCl3) with δ values of 6.90 (d, 2H), 6.63 (d, 2H), 4.20-4.50 (m, 1H), 4.14 (q, 2H), 3.76-3.00 (m, 2H), 1.36 (s, 9H), and 1.20 (t, 3H), respectively.