705263-10-1

6-Bromopyrazolo[1,5-a]pyrimidine is a reactant in the synthesis of LDN-212854, a selective and potent inhibitor of the BMP type I receptor kinases.

Using 2-bromomalonaldehyde (15.1 g, 100 mmol) and 3H-pyrazol-3-amine (8.3 g, 100 mmol) as raw materials, 120 mL of ethanol was added to a 250 mL round bottom flask and the mixture was cooled down to 0 °C. Subsequently, 12 mL of concentrated hydrochloric acid was slowly added and after returning to room temperature, stirring was continued for 2 hours. During the reaction, a yellowish solid precipitated. Upon completion of the reaction, the solid was collected by direct filtration and the filter cake was washed sequentially with saturated NaHCO3 solution and distilled water. After drying, 17 g of the intermediate 6-bromopyrazolo[1,5-a]pyrimidine was obtained in 86% yield.

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