Water → 4-Bromo-6-chloro-2,3-dihydropyridazin-3-one

Participants

Reaction Conditions

Reaction Steps

To a cooled solution (0-5° C.) of NaNO2 (2.4 equiv.) in H2SO4 conc. (23 equiv.) was added 4-bromo-6-chloropyridazin-3-amine (1.0 equiv.) in acetic acid (0.25 M). The reaction mixture was stirred at 0° C. for 30 min before warming to room temperature and stirring for 1 hour. Water was added and stirred at room temperature for a further 4 hours. The reaction mixture was then extracted with ethyl acetate, dried over MgSO4 and concentrated in vacuo to yield a brown oil. The oil was further purified by silica gel column chromatography eluting with 100% heptanes to 80% ethyl acetate/heptanes to yield 4-bromo-6-chloropyridazin-3(2H)-one as an off-white solid in 83% yield. LCMS (m/z) (M+H)=208.9/210.9, Rt=0.42 min. 1H NMR (400 MHz, <dmso>) δ ppm 8.08-8.32 (m, 1H) 13.25-13.71 (m, 1H).

Provenance & Evidence