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

Participants

Reaction Conditions

Reaction Steps

A mixture of (3-o-tolyl-isoxazol-4-yl)-carbamic acid tert-butyl ester (500 mg, 1.82 mmol, 1.0 equiv), 4M HCl in dioxane (4 mL) in 1,4-dioxane (5 mL) was stirred at ambient temperature for 22 hours and at 40° C. for 1 hour. The mixture was concentrated under vacuum affording a residue which was dissolved in dichloromethane (15 mL) and treated with diisopropylethylamine (523 mg, 4.05 mmol, 2.2 equiv). The mixture was cooled with an ice-bath and a solution of 5-chloropyrazolo[1,5-a]pyrimidine-3-carbonyl chloride (1.82 mmol, 1.0 equiv) in dichloromethane (10 mL) was added dropwise. The reaction mixture was warmed to room temperature after the addition. After 65 hours, the solution was sequentially washed with 1M HCl aqueous solution, saturated aqueous sodium bicarbonate solution, water, and saturated aqueous sodium chloride solution. The organic was dried over anhydrous sodium sulfate, filtered, and concentrated under vacuum. The residue was triturated (methanol) to give 444 mg (70%) of 5-chloro-pyrazolo[1,5-a]pyrimidine-3-carboxylic acid (3-o-tolyl-isoxazol-4-yl)-amide. LCMS (ESI) m+H=354.2 (mono Cl); 1H NMR (300 MHz, DMSO-d6) δ: 9.47 (s, 1H), 9.36 (d, 1H), 9.11 (s, 1H), 8.72 (s, 1H), 7.53-7.40 (m, 4H), 7.37 (d, 1H), 2.31 (s, 3H).

Provenance & Evidence