Imidazole → ethyl 6-((S)-1-(tert-butoxy)-2-ethoxy-2-oxoethyl)-7-(4-(((R)-5-((tert-butyldiphenylsilyl)oxy)hexyl)oxy)-4-methylpiperidin-1-yl)-5-methylpyrazolo[1,5-a]pyrimidine-2-carboxylate

Participants

Reaction Steps

To a solution of ethyl 6-((S)-1-(tert-butoxy)-2-ethoxy-2-oxoethyl)-7-(4-(((R)-5-hydroxyhexyl)oxy)-4-methylpiperidin-1-yl)-5-methylpyrazolo[1,5-a]pyrimidine-2-carboxylate (800 mg, 1.387 mmol) in DMF (10 mL) at 0° C. was added imidazole (142 mg, 2.081 mmol) followed by tert-butylchlorodiphenylsilane (0.533 mL, 2.081 mmol) and the resulting mixture was stirred at room temp for 16 h. Water (20 mL) was then added and the mixture was extracted with ether (2×25 mL). Ether layer was then washed with brine (25 mL), dried (Na2SO4), filtered and concentrated. The residue was purified via Biotage (0-10% EtOAc/hexane) to afford ethyl 6-((S)-1-(tert-butoxy)-2-ethoxy-2-oxoethyl)-7-(4-(((R)-5-((tert-butyldiphenylsilyl)oxy)hexyl)oxy)-4-methylpiperidin-1-yl)-5-methylpyrazolo[1,5-a]pyrimidine-2-carboxylate (1 g, 1.227 mmol, 88% yield) as viscous liquid. 1H NMR (400 MHz, CDCl3) δ 7.69 (dd, J=8.0, 1.5 Hz, 4H), 7.47-7.28 (m, 6H), 7.01 (s, 1H), 5.82 (br. s., 1H), 4.50-4.38 (m, 2H), 4.31-4.07 (m, 2H), 3.94-3.77 (m, 1H), 3.41-3.24 (m, 3H), 2.61 (s, 3H), 1.88 (br. s., 2H), 1.67 (br. s., 1H), 1.54 (br. s., 1H), 1.51-1.39 (m, 5H), 1.30 (s, 3H), 1.26-1.23 (m, 6H), 1.22 (s, 9H), 1.08 (s, 3H), 1.06 (s, 9H). 4 missing piperidine hydrogens. LCMS (M+H)=816.4.

Provenance & Evidence