Boron tribromide → Pyrazolo[1,5-a]pyrimidine-3-carboxylic acid [2-bromo-4-(5-chloro-2-hydroxy-phenyl)-thiazol-5-yl]-amide

Participants

Reaction Conditions

Reaction Steps

To a solution of pyrazolo[1,5-a]pyrimidine-3-carboxylic acid [2-bromo-4-(5-chloro-2-methoxy-phenyl)-thiazol-5-yl]-amide (4.3 g, 9.3 mmol) in DCM (90 mL) at −78° C. under an atmosphere of N2 was added boron tribromide (1M in DCM, 45 mL, 45 mmol) dropwise. The mixture was stirred at −78° C. for 1 hour and then allowed slowly to room temperature and stirred for a further 16 hours. The mixture was poured cautiously onto an aqueous solution of sodium hydrogen carbonate, stirred for 15 mins, filtered and the solid collected and dried to afford pyrazolo[1,5-a]pyrimidine-3-carboxylic acid [2-bromo-4-(5-chloro-2-hydroxy-phenyl)-thiazol-5-yl]-amide as a beige solid (6 g, >100%). LCMS (Method 3) [M+H]+=450.1, RT=3.71 min. 1H NMR (400 MHz, DMSO-d6) δ: 15.96 (s, 1H), 9.18 (dd, 1H, J=1.6, 6.9 Hz), 8.70 (dd, 1H, J=1.8, 4.0 Hz), 8.59 (s, 1H), 7.80 (d, 1H, J=2.8 Hz), 7.15 (dd, 1H, J=4.0, 7.1 Hz), 7.05 (dd, 1H, J=2.8, 8.6 Hz), 6.77 (d, 1H, J=8.6 Hz).

Provenance & Evidence