[Synthesis]
Boc-L-aspartyl (OBn) (OMe) 14 (5.88 g, 17.43 mmol) was used as a raw material and dissolved in methanol (20 mL) in a 50 mL round bottom flask. A 10% palladium-carbon catalyst was added to the reaction system under nitrogen protection. Subsequently, the gas in the reaction vessel was replaced three times with nitrogen and then three times with hydrogen. 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) as a colorless gelatinous liquid (4.1 g, 95% yield). The product had a rotativity [α]21D = 34 (c 0.1, CHCl3).1H NMR (CDCl3, 400MHz) δ: 1.43 (s, 9H), 2.83-2.86 (d, 1H, J = 16.92Hz), 3.01-3.05 (d, 1H, J = 16.68Hz), 3.74 (s, 3H), 4.57 (s, 1H), 4.57 (s, 1H). 1H), 5.55-5.57 (d, 1H, J = 8.12Hz), 10.45 (s, 1H).13C NMR (CDCl3, 100MHz) δ: 28.3, 36.6, 49.7, 52.8, 80.5, 155.5, 171.5, 176.0. IR (KBr) νmax: 3366, 2980, 1719, 1506, 1440. 1719, 1506, 1440, 1395, 1368, 1222, 1165, 1060, 1008, 864, 764, 587 cm-1. |
[References]
[1] Organic and Biomolecular Chemistry, 2007, vol. 5, # 9, p. 1459 - 1465
[2] Tetrahedron Letters, 2014, vol. 55, # 14, p. 2274 - 2276
[3] Bioorganic and Medicinal Chemistry Letters, 2005, vol. 15, # 1, p. 15 - 20
[4] Bioorganic and Medicinal Chemistry Letters, 2010, vol. 20, # 2, p. 586 - 590
[5] Carbohydrate Research, 2013, vol. 382, p. 36 - 42 |