tert-Butylhydrazine monohydrochloride → 6-t-Butylpyrido[2,3-d]pyridazin-5(6H)-one

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Reaction Steps

In acetic acid-water (1:1) (5 ml) was dissolved ethyl 2-formyl-3-pyridinecarboxylate (1.3 g) followed by addition of t-butylhydrazine hydrochloride (1.8 g), and the mixture was refluxed with stirring for 1 hour. This reaction mixture was cooled to room temperature, adjusted to pH 5.0 with saturated aqueous NaHCO3 solution, and extracted with dichloromethane. The organic layer was washed with saturated aqueous NaCl solution, dried over anhydrous magnesium sulfate, and concentrated. The residue was dissolved in acetic acid (2 ml) and refluxed for 1 hour. This reaction mixture was cooled, adjusted to pH 5.0 with saturated aqueous NaHCO3 solution, and extracted with dichloromethane. The organic layer was washed with saturated aqueous NaCl solution, dried over anhydrous magnesium sulfate, and concentrated. The residue was purified by silica gel chromatography (n-hexane: ethyl acetate =1:1). White powder, 1.2 g. 1H-NMR (CDCl3) δ: 1.73(9H,s), 7.64(1H,dd,J=8.2&4.4Hz), 8.38(1H,s), 8.69(1H,d,J=8.2Hz), 9.03(1H,d,J=4.4Hz).

Provenance & Evidence