Hydrochloric Acid → 5-Chloro-pyrazolo[1,5-a]pyrimidine-3-carboxylic acid [5-(2-trifluoromethyl-phenyl)-isoxazol-4-yl]-amide

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Reaction Conditions

Reaction Steps

A mixture of [5-(2-trifluoromethyl-phenyl)-isoxazol-4-yl]-carbamic acid tert-butyl ester (345 mg, 1.05 mmol, 1.0 equiv), 4M HCl in dioxane (2 mL) in 1,4-dioxane (3 mL) was heated to 40° C. for 20 hours. The mixture was concentrated under vacuum affording a residue which was dissolved in dichloromethane (12 mL) and treated with diisopropylethylamine (271 mg, 2.10 mmol, 2.0 equiv). The mixture was cooled with an ice-bath, and a solution of 5-chloropyrazolo[1,5-a]pyrimidine-3-carbonyl chloride (1.05 mmol, 1.0 equiv) in dichloromethane (6 mL) was added dropwise. The resultant mixture was stirred at ambient temperature for 18 hours. The solution was washed sequentially with 1M HCl aqueous solution, saturated aqueous sodium bicarbonate solution and water. The collected organic was dried over anhydrous sodium sulfate, filtered, and concentrated under vacuum. The residue was triturated (methanol), and the isolated solid was washed with methanol and diethyl ether before drying under vacuum to give 367 mg (86%) of 5-chloro-pyrazolo[1,5-a]pyrimidine-3-carboxylic acid [5-(2-trifluoromethyl-phenyl)-isoxazol-4-yl]-amide. LCMS (ESI) m+H=408.0 (mono Cl); 1H NMR (400 MHz, DMSO-d6) δ: 9.50 (s, 1H), 9.35 (d, 1H), 9.22 (s, 1H), 8.71 (s, 1H), 8.03 (d, 1H), 7.97-7.82 (m, 3H), 7.38 (d, 1H).

Provenance & Evidence