Hydrochloric Acid → 6-((S)-1-(tert-butoxy)-2-ethoxy-2-oxoethyl)-7-(8-fluoro-5-methylchroman-6-yl)-5-methylpyrazolo[1,5-a]pyrimidine-2-carboxylic acid

Participants

Reaction Steps

To a solution of ethyl 6-((S)-1-(tert-butoxy)-2-ethoxy-2-oxoethyl)-7-(8-fluoro-5-methylchroman-6-yl)-5-methylpyrazolo[1,5-a]pyrimidine-2-carboxylate (4 g, 6.07 mmol) in THF (40 mL) was added 1N NaOH (6.07 mL, 6.07 mmol) and the resulting mixture was stirred at rt for 16 h. At this point the LCMS indicated about 70% conversion, so additional 1N NaOH (2.5 mL, 2.5 mmol) was added and the mixture was stirred for another 2 h. At this point LCMS indicated progression of reaction (˜90% conversion) along with small amount of di-acid. Water (20 mL) was then added to the reaction mixture and it was acidified with 1N HCl (10 mL). This aqueous solution was extracted with ether (2×100 mL), washed with brine (50 mL), dried (Na2SO4), filtered and concentrated in vacuo to afford 6-((S)-1-(tert-butoxy)-2-ethoxy-2-oxoethyl)-7-(8-fluoro-5-methylchroman-6-yl)-5-methylpyrazolo[1,5-a]pyrimidine-2-carboxylic acid (2.7 g, 5.41 mmol, 89% yield) as off-white solid. 1H NMR (500 MHz, CDCl3) δ 7.21 (s, 1H), 6.85 (d, J=10.7 Hz, 1H), 5.00 (s, 1H), 4.36 (t, J=4.4 Hz, 2H), 4.19-4.12 (m, 2H), 2.81 (s, 3H), 2.80-2.74 (m, 2H), 2.20 (dd, J=6.3, 4.1 Hz, 2H), 1.83 (s, 3H), 1.24-1.20 (m, 3H), 1.18 (s, 9H). LCMS (M+H)=500.4.

Provenance & Evidence