N-bromobutanimide → Ethyl 6-bromo-3-methoxy-1-methyl-2-oxo-1,2-dihydropyridine-4-carboxylate
Reaction equation
[CH3:1][O:2][C:3]1[C:4](=[O:15])[N:5]([CH3:14])[CH:6]=[CH:7][C:8]=1[C:9]([O:11][CH2:12][CH3:13])=[O:10].C1C(=O)N([Br:23])C(=O)C1>ClCCCl>[Br:23][C:6]1[N:5]([CH3:14])[C:4](=[O:15])[C:3]([O:2][CH3:1])=[C:8]([C:9]([O:11][CH2:12][CH3:13])=[O:10])[CH:7]=1Participants
4
Procedure
To a solution of Intermediate 1 (109 mg, 0.516 mmol) in DCE (2.0 mL) was added NBS (110 mg, 0.619 mmol). The reaction mixture was stirred at rt overnight and then was concentrated under reduced pressure. The residue was diluted with EtOAc, washed with water and brine, dried over anhydrous sodium sulfate, filtered and evaporated under reduced pressure. The residue was dissolved in a small amount of DCM and charged to a 12 g silica gel cartridge which was eluted with a 25 min gradient from 0-100% EtOAc/hexane to give Intermediate 18 (138 mg, 0.476 mmol, 69% yield) as a white solid. HPLC/MS (Method D) RT=1.4 min, [M+1]+ 291.9; 1H NMR (400 MHz, CHLOROFORM-d) δ ppm 7.29 (1H, s), 4.42 (2H, q, J=7.28 Hz), 3.99 (3H, s), 3.55 (3H, s), 1.39 (3H, t, J=7.15 Hz).