Phenylhydrazine → 1-(4-Bromo-2,5-difluorophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

Participants

Reaction Conditions

Reaction Steps

A mixture of 3-acetyl-1-(4-bromo-2,5-difluorophenyl)-5-methoxypyridazin-4(1H)-one (3.57 g, 10 mmol) and N,N-dimethylformamide dimethyl acetal (16 mL) was stirred at 100° C. for 5 h. After cooling to room temperature, the reaction mixture was concentrated under reduced pressure. The residue was dissolved in AcOH (20 mL) and added phenylhydrazine (2.0 mL, 20 mmol). This mixture was stirred at 130° C. for 3 h. After cooling to room temperature, the reaction mixture was concentrated under reduced pressure. The residue was purified by silica gel column chromatography eluting with hexane/AcOEt (1/0 to 0/1) and recrystallized from iPr2O/AcOEt to give the title compound (1.05 g, 23% yield) as a pale yellow solid: mp 211-213° C.; 1H NMR (300 MHz, DMSO-d6): δ ppm 3.77 (3H, s), 7.02 (1H, d, J=1.9 Hz), 7.09 (1H, dd, J=8.9, 6.6 Hz), 7.22-7.62 (5H, m), 7.80 (1H, d, J=1.9 Hz), 8.07 (1H, dd, J=10.2, 6.0 Hz), 8.49 (1H, d, J=2.3 Hz). LC-MS (ESI) m/z 460 [M+H]+. Anal. Calcd for C20H13BrF2N4O2: C, 52.31; H, 2.85; N, 12.20. Found: C, 52.51; H, 2.95; N, 12.20.

Provenance & Evidence