The condensation of 2-[6-(dimethylamino)pyridin-3-yl]acetonitrile (I) with ethyl acetate (II) by means of NaH in THF gives 2-[6-(dimethylamino)pyridin-3-yl]-3-oxobutyronitrile (III), which is treated with hydrazine in refluxing ethanol/water to yield the corresponding hydrazone (IV). The cyclization of (IV) with ethyl acetoacetate (V) in refluxing dioxane affords 3-[6-(dimethylamino)pyridin-3-yl]-2,5-dimethylpyrazolo[2,3-a]pyrimidin-7-ol (VI), which is treated with refluxing POCl3 to provide the expected 7-chloro derivative (VII). Finally, this compound is treated with dipropylamine (VIII) in refluxing acetonitrile to furnish the target dipropylamino derivative.

Aminopyrazole (I) was cyclized to pyrazolopyrimidine (III) by means of ethyl acetoacetate (II) in refluxing dioxan. Chlorination of (II) with POCl3 produced the corresponding chloro derivative (IV). This was then heated with an excess of amine (V) in a sealed vessel at 100 C to afford the target compound, which was isolated as the hydrochloride salt.