N-boc Asp(OH)Ome

80963-12-8

98045-03-5

Boc-L-aspartyl (OBn)(OMe)14 (5.88 g, 17.43 mmol) was dissolved in methanol (20 mL) in a 50 mL round-bottomed flask and 10% palladium carbon catalyst was added under nitrogen protection. The reaction system was replaced three times with nitrogen and then three times with hydrogen. Subsequently, the reaction mixture was stirred under hydrogen atmosphere and atmospheric pressure for 6 hours. Upon completion of the reaction, the catalyst was removed by filtration and the filtrate was concentrated to afford the target product (S)-3-((tert-butoxycarbonyl)amino)-4-methoxy-4-oxobutanoic acid (Compound 15) in the form of a colorless gel (4.1 g, 95% yield). The specific optical rotation [α]21D of the product was 34 (c 0.1, CHCl3).1H NMR (CDCl3, 400 MHz) δ: 1.43 (s, 9H), 2.83-2.86 (d, 1H, J = 16.92 Hz), 3.01-3.05 (d, 1H, J = 16.68 Hz), 3.74 (s, 3H), 4.57 (s , 1H), 5.55-5.57 (d, 1H, J = 8.12 Hz), 10.45 (s, 1H).13C NMR (CDCl3, 100 MHz) δ: 28.3, 36.6, 49.7, 52.8, 80.5, 155.5, 171.5, 176.0. IR (KBr) ν: 3366, 2980, 1719 , 1506, 1440, 1395, 1368, 1222, 1165, 1060, 1008, 864, 764, 587 cm-1.