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

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).

1. temperatureat reflux for 4 h
2. temperaturethe mixture heated
3. temperatureat reflux for a further 0.5 h
4. concentrationconcentrated in vacuo
5. customThe residue was triturated in methanol
6. customThe solid thus obtained
7. washwas washed with cold methanol, ethyl acetate, and hexanes

ORD record

ord-32bf6f119d3a4059b04189d704ef9ec3

Source dataset

uspto-grants-2016_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09365578B2