Water → 3-Bromopyrazolo(1,5-a)pyrimidine

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Reaction Steps

A solution of 3-amino-4-bromopyrazole (2.0 g, 12 mmol) and 1,1,3,3-tetramethoxypropane (4.1 mL, 25 mmol) in acetic acid (5 mL) was heated at reflux for 4 h. Water (2 mL) was added and the mixture heated at reflux for a further 0.5 h, allowed to cool to ambient temperature and concentrated in vacuo. The residue was triturated in methanol. The solid thus obtained was washed with cold methanol, ethyl acetate, and hexanes to provide 3-bromopyrazolo[1,5-a]pyrimidine as a brownish solid in 39% yield (0.953 g): 1H NMR (300 MHz, DMSO-d6) δ9.13 (d, J=6.5 Hz, 1H), 8.61 (s, 1H), 8.35 (s, 1H), 7.19-7.02 (m, 1H); MS (ES+) m/z 197.9 (M+1), 199.9 (M+1).

Provenance & Evidence