3-broMo-5,7-dichloropyrazolo(1,5-a)pyriMidine

57489-77-7

114040-06-1

General procedure for the synthesis of 3-bromo-5,7-dichloropyrazolo[1,5-a]pyrimidines from 5,7-dichloropyrazolo[1,5-a]pyrimidines: To a solution of 5,7-dichloropyrazolo[1,5-a]pyrimidines (1 g, 5.32 mmol) in acetonitrile (20 mL) was added N-bromosuccinimide (1.04 g, 5.85 mmol) and ammonium ceric nitrate (0.029 g, 0.053 mmol). The reaction mixture was heated to reflux for 1 hour. After completion of the reaction, the reaction mixture was washed sequentially with 10% aqueous sodium bisulfite (30 mL) and brine (20 mL). The organic phase was dried with magnesium sulfate and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography with 20% ether/hexane as eluent to afford 3-bromo-5,7-dichloropyrazolo[1,5-a]pyrimidine as a yellow solid (1.33 g, 92% yield). δH (400 MHz; d4-CDCl3) 8.22 (1H, s), 7.04 (1H, s).