N-bromobutanimide → 3-Bromo-5,7-dichloropyrazolo[1,5-a]pyrimidine

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Reaction Steps

To a solution of 5.3 g of 5,7-dichloropyrazolo(1,5-a)pyrimidine in 70 ml of chloroform was added portionwise 6 g of N-bromosuccinimide while keeping the temperature below 40° C. The resulting solution was refluxed for 30 minutes and was then stirred at room temperature for 12 hours. The suspension was then filtered. The filtrate was washed with 50 ml of cold 10% sodium hydroxide aqueous solution twice and was then dried over MgSO4. The chloroform solution was then concentrated under reduced pressure to give 7.47 g of the desired product, m.p. 73°-75° C.

Provenance & Evidence