[CH3:1][C:2]1[C:12]([N+:13]([O-:15])=[O:14])=[CH:11][C:5]2[NH:6][C:7](=[O:10])[CH2:8][O:9][C:4]=2[CH:3]=1.C([O-])([O-])=O.[K+].[K+].[CH2:22]([O:24][C:25](=[O:29])[CH:26](Br)[CH3:27])[CH3:23].CC#N>CC(C)=O.O>[CH2:22]([O:24][C:25](=[O:29])[CH:26]([N:6]1[C:5]2[CH:11]=[C:12]([N+:13]([O-:15])=[O:14])[C:2]([CH3:1])=[CH:3][C:4]=2[O:9][CH2:8][C:7]1=[O:10])[CH3:27])[CH3:23]
To 7-methyl-6-nitro-4H-benzo[1,4]oxazin-3-one (50% purity; 0.870 g, 1.44 mmol) and K2CO3 (1.15 g, 8.36 mmol) in acetone (20 mL) was added 2-bromo-propionic acid ethyl ester (1.5 g, 8.36 mmol) and the mixture was heated at 70° C. for 5 h. The reaction mixture was cooled to ambient temperature and the solvent was removed in vacuo and the residue was dissolved in DCM (15 mL). The solution was washed with water (15 mL), dried over anhydrous Na2SO4, filtered and the filtrate was evaporated in vacuo. The residue was purified by chromatography on silica gel (eluting with 20% EtOAc in petroleum ether) to give a mixture of the title compound as a yellow solid (total 0.5 g crude, 48% desired product as indicated by HPLC at 254 or 220 nm), HPLC (Column: Ultimate XB-C18, 3 um, 50×3.0 mm; Mobile phase: MeCN (0.02% TFA) in water (0.04% TFA), from 30% to 90% within 7 min; Flow rate: 1.5 mL/min; Wavelength: 220 nm) Rt=3.42 min.), which was used directly in the next step.
불러오는 중…
