Potassium Hydroxide → 1-(2-chlorophenyl)-3-(1-piperazinyl)-1H-indazole

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Reaction Steps

A stirred mixture of 28.7 g of 4-[1-(2-chlorophenyl)-1H-indazol-3-yl]-1-piperazine carboxylic acid ethyl ester, 450 ml of 2-methoxymethanol, and a solution of 25 g of potassium hydroxide in 250 ml of water, was refluxed for 16 hours, cooled to ambient temperature, concentrated to about one-third of its volume, poured into water, and extracted with ethyl acetate. The extract was washed with water, dried over anhydrous magnesium sulfate, and concentrated to yield 1-(2-chlorophenyl)-3-(1-piperazinyl)-1H-indazole as an oil. The oil was dissolved in anhydrous diethyl ether and treated with ethereal hydrogen chloride to precipitate the hydrochloride salt. The salt was recrystallized from acetonitrile to yield 18.8 g (72%) of 1-(2-chlorophenyl)-2-(1-piperazinyl)-1H-indazole hydrochloride. Recrystallization from isopropyl alcohol-diethyl ether afforded the analytical sample, m.p. 197°-199°.

Provenance & Evidence