126352-69-0

1225387-53-0

109-64-8

126352-69-0

To a solution of 3H-pyrazol-3-amine (9.8 g, 0.1 mol) and triethylamine (TEA, 36.0 g, 0.3 mol) in 1,4-dioxane (200 mL) was added 1,3-dibromopropane (26.3 g, 0.1 mol). The reaction mixture was stirred at 110 °C for 5 hours. After the reaction was complete, the mixture was filtered. The filtrate was concentrated to dryness. The residue was purified by silica gel column chromatography (eluent: dichloromethane/methanol = 100/1) to afford 4,5,6,7-tetrahydropyrazolo[1,5-a]pyrimidine (5.3 g, yield: 36%) as a white solid.1H NMR (300 MHz, CDCl3): δ = 7.18 (s, 1H), 5.26 (s, 1H), 4.22-4.00 (m, 3H), 3.26-3.22 (m, 2H), 2.11-2.03 (m, 2H).