Hydroxyamine hydrochloride → 7-Bromo-4-(N-hydroxy-imino)-1-(2-pyridyl)-3,6,6-trimethyl-4,5,6,7-tetrahydroindazole

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Reaktionsschritte

A mixture of 7-bromo-1-(2-pyridyl)-3,6,6-trimethyl-4-oxo-4,5,6,7-tetrahydro-indazole (0.3 g, 0.9 mmol), prepared as described in example 4, hydroxylamine hydrochloride (0.37 g, 4.5 mmol), and sodium acetate (0.44 g, 5.4 mmol) in 1,4-dioxane (50 ml) was heated under reflux for about 4 hours. Additional hydroxylamine hydrochloride (0.123 g, 1.6 eq) and sodium acetate (0.146 g, 2 eq) were added and heating was continued for further 4 hours. The reaction mixture was poured onto ice/water and extracted with dichloromethane. The combined organic layers were washed with brine, dried over sodium sulfate and evaporated. The residue was chromatographed on silica gel (cyclohexane:ethyl acetate=90:10) to give the title compound as a colourless solid (0.14 g, 45%): m.p. 195-196° C.

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