[CH3:1][C:2]1[CH:21]=[CH:20][C:5]([N:6]=[CH:7][C:8]2[CH:13]=[C:12]([O:14][CH3:15])[C:11]([O:16][CH3:17])=[C:10]([O:18][CH3:19])[CH:9]=2)=[CH:4][CH:3]=1.[BH4-].[Na+]>C(O)C>[CH3:1][C:2]1[CH:3]=[CH:4][C:5]([NH:6][CH2:7][C:8]2[CH:13]=[C:12]([O:14][CH3:15])[C:11]([O:16][CH3:17])=[C:10]([O:18][CH3:19])[CH:9]=2)=[CH:20][CH:21]=1To a solution of (108a) (6.0 g, 21.1 mmol) in ethanol (100 mL) was added NaBH4 (4.06 g, 98%, 105 mmol) in portions. The reaction mixture was stirred at reflux under argon for 2 h. The solvent was removed under reduced pressure. Saturated aqueous NaCl (30 mL) was added to the residue and the mixture extracted with ether (100, 40 and 40 mL). The combined ether layer was washed with saturated NaCl solution (30 mL), and dried over anhydrous Na2SO4. Evaporation of the filtrate gave 109a (5.6 g, 92.7%) as white crystals: mp 94°-6° C. after recrystallization from ethanol. 1H NMR (200 MHz, CDCl3) δ7.00 (d, J=8 Hz, 2H), 6.61 (s, 2H), 6.58 (d, J=8 Hz, 2H), 4.23 (s, 2H), 3.84 (s, 9H), 2.24 (s, 3H). CIMS (isobutane) m/e 288 (MH+ 76).
Wird geladen…