Chlorosuccinimide → 3,7-Dichloro-6-(2-chloroethyl)-5-methylpyrazolo[1,5-a]-pyrimidin

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Reaction Steps

1.60 g (12 mmoles) of N-chlorosuccinimide were added to a solution of 2.30 g (10 mmoles) of 7-chloro-6-(2-chloroethyl)-5-methylpyrazolo[1.5-a]pyrimidine (prepared as described in Example 3) in 10 ml of chloroform, and the resulting mixture was heated under reflux, with stirring, for one hour. At the end of this time, the reaction mixture was washed with a 2N aqueous solution of potassium hydroxide and then with water, after which it was dried over anhydrous sodium sulfate and then concentrated by evaporation under reduced pressure. The residue was purified by column chromatography through alumina (eluted with chloroform) and recrystallized from diisopropyl ether to afford 1.56 g (yield 59%) of the title compound as light yellow needles, melting at 115°-117° C.

Provenance & Evidence