[N+:1]([O-:4])(O)=[O:2].[CH3:5][O:6][C:7](=[O:21])[C:8]1[CH:13]=[C:12]([Cl:14])[C:11]([NH:15][C:16](=[O:18])[CH3:17])=[CH:10][C:9]=1[O:19][CH3:20]>CCOC(C)=O>[CH3:5][O:6][C:7](=[O:21])[C:8]1[CH:13]=[C:12]([Cl:14])[C:11]([NH:15][C:16](=[O:18])[CH3:17])=[C:10]([N+:1]([O-:4])=[O:2])[C:9]=1[O:19][CH3:20]Fuming nitric acid (33 mL) was added dropwise at 20° C. to compound 10 (13.0 g, 0.05 mol) over 15 min. After stirring for an additional 10 min at that temperature, the mixture was poured into ice water and EtOAc (100 mL) was added. After separating the organic phase, the aqueous phase was extracted with EtOAc. The combined organic phases were washed with brine, dried over MgSO4 and concentrated. Drying under hv yielded 14.0 g (91%) of 11 as a beige solid. 1H NMR (300 MHz, DMSO-d6): δ 2.01 (s, 3H), 3.84 (s, 3H), 3.87 (s, 3H), 8.12 (s, 1H), 10.30 (s, 1H).
불러오는 중…