Trifluoroacetic acid → 1-(3-(2-Amino-6-fluoropyrazolo[1,5-a]pyrimidine-3-carboxamido)-5-fluoropyridin-4-yl)piperidine-4-carboxylic acid

Participants

Reaction Steps

To a suspension of tert-butyl 1-[3-[(2-amino-6-fluoro-pyrazolo[1,5-a]pyrimidine-3-carbonyl)amino]-5-fluoro-4-pyridyl]piperidine-4-carboxylate 28 (69.7 g, 147.2 mmol) in DCM (348.5 mL) and triethylsilane (18.83 g, 25.87 mL, 161.9 mmol) was added TFA (151.1 g, 102.1 mL, 1.325 mol) (mixture sets solid on initial addition of TFA then goes into solution after complete addition). Resulting orange solution was stirred at room temperature overnight. Additional TFA (16.78 g, 11.34 mL, 147.2 mmol) was added and the mixture stirred at room temperature for 2 h. Mixture then heated at 40° C. for 20 mins to force reaction to completion. Mixture was concentrated in vacuo, chloroform (300 mL) was added and mixture again concentrated in vacuo to leave an orange solid suspension. Mixture triturated in DCM (approx. 200 mL), stirred for 20 mins then solid collected by filtration, washed with minimal DCM and dried by suction to leave a yellow solid. Filtrate was concentrated in vacuo, residue re-slurried in DCM (approx 50 mL), stirred for 20 mins then solid collected by filtration, washed with minimal DCM and dried by suction to leave a yellow solid which was combined with first crop of solid. Solid dried under vacuum overnight to leave desired product 29 as a yellow solid (82.8 g, 96%). 1H NMR (500 MHz, DMSO-d6) δ 10.44 (s, 1H), 9.59 (s, 1H), 9.50 (dd, 1H), 8.84 (dd, 1H), 8.33 (d, 1H), 3.13-3.10 (m, 4H), 2.57-2.47 (masked signal, 1H) and 2.08-1.93 (m, 4H). MS (ES+) 418.1.

Provenance & Evidence