C(O)=O.[NH:4]1[CH2:7][CH:6]([CH2:8][C:9]([O:11][CH2:12][CH3:13])=[O:10])[CH2:5]1.CCN(CC)CC.[O:21](C(OC(C)(C)C)=O)[C:22]([O:24][C:25]([CH3:28])([CH3:27])[CH3:26])=O>CN(C=O)C>[C:22]([N:4]1[CH2:7][CH:6]([CH2:8][C:9]([O:11][CH2:12][CH3:13])=[O:10])[CH2:5]1)([O:24][C:25]([CH3:28])([CH3:27])[CH3:26])=[O:21]A stirred solution of 131 (10.3 mmol), DMF (50 mL), and NEt3 (5.0 mL, 36.0 mmol) at 0° C. was treated with BOC2O (2.5 g, 11.3 mmol) followed by removal of the cooling bath. After 20 h, the reaction mixture was diluted with EtOAc and then washed with H2O, 5% KHSO4, sat. NaHCO3, and brine, dried (MgSO4), and concentrated. Flash chromatography (silica, 30% EtOAc/hexanes) gave 132 (1.0 g) as a colorless oil. Rf 0.44 (silica, EtOAc/hexanes). 1H NMR (300 MHz, CDCl3) δ 4.13 (q, J=7 Hz, 2H), 4.01 (m, 2H), 3.60 (dd, J=9 and 6 Hz, 1H), 2.88 (m, 1H), 2.61 (d, J=8 Hz, 2H), 1.44 (s, 9H) 1.25 (t, J=7H, 3H). ##STR57##
Wird geladen…
