6-Bromo-3,4-dihydro-1H-[1,8]naphthyridin-2-one

335031-10-2

129686-16-4

General procedure for the synthesis of 6-bromo-3,4-dihydro-1H-[1,8]naphthyridin-2-one from methyl 6-bromo-2-oxo-1,2,3,4-tetrahydro-1,8-naphthyridine-3-carboxylate: (c) 6-Bromo-3,4-dihydro-1H-1,8-naphthyridin-2-one (2.00 g, 7.0 mmol) was dissolved in CH3OH (75 mL) and 1.0 M NaOH solution (30 mL) was added. The reaction mixture was heated to reflux for 4 hours and subsequently cooled to room temperature. The reaction solution was neutralized with 1.0 M HCl (30 mL) and heated to reflux again overnight. The reaction slurry was concentrated to dryness and the residue was suspended with 95:5 CHCl3/CH3OH. The insoluble material was removed by filtration and the filtrate was concentrated to afford 6-bromo-3,4-dihydro-1H-[1,8]naphthyridin-2-one (1.40 g, 88% yield) as an off-white solid: mass spectra (electrospray ionization) m/e 228 (M + H)+.