p-Toluenesulfonic acid → 6-Bromo-2-tert-butylpyrazolo[1,5-a]pyrimidine

Participants

Reaction Conditions

Reaction Steps

3-tert-Butyl-1H-pyrazol-5-amine (9 g, 64.7 mmol) was dissolved in BuOH (100 ml). 2-Bromomalonaldehyde (9.76 g, 64.7 mmol) and p-TsOH*H2O (615 mg, 3.23 mmol) were added at room temperature. The mixture was stirred for 16 hours at 100° C. The reaction mixture was evaporated to dryness and the residue was purified by flash chromatography on silica gel (120 gr, 0% to 40% EtOAc in heptane) and crystallization with a small volume of diisopropylether. The crystals were washed with diisopropylether and dried for 1 hour at 50° C. and <20 mbar. The desired compound was obtained as a light yellow solid (9.5 g, 58% yield), MS: m/e=256.1/254.1 (M+H+).

Provenance & Evidence