Diisopropylethylamine → Methyl 2-(7-(4-(allyloxy)-4-methylpiperidin-1-yl)-2-bromo-5-methylpyrazolo[1,5-a]pyrimidin-6-yl)acetate

Participants

Reaction Steps

A solution of methyl 2-(2-bromo-7-chloro-5-methylpyrazolo[1,5-a]pyrimidin-6-yl)acetate (prepared according to the procedure for intermediate 4 starting from 3-bromo-1H-pyrazol-5-amine; 13.4 g, 41.9 mmol, 1 equiv), 4-(allyloxy)-4-methylpiperidine (7.16 g, 46.1 mmol, 1.1 equiv), and DIEA (17.6 mL, 101 mmol, 2.4 equiv) in DMF (84 mL) was heated at 60° C. for 2 h. The reaction was then added to water and extracted with ether (×2). Combined ether extracts dried (MgSO4) and concentrated in vacuo. The crude product was purified by silica gel flash chromatography (0-50% EtOAc/hex) to provide methyl 2-(7-(4-(allyloxy)-4-methylpiperidin-1-yl)-2-bromo-5-methylpyrazolo[1,5-a]pyrimidin-6-yl)acetate (17.7 g, 97%). 1H NMR (500 MHz, CDCl3) δ 6.52 (s, 1H), 6.02 (ddt, J=17.2, 10.4, 5.2 Hz, 1H), 5.43 (dd, J=17.2, 1.6 Hz, 1H), 5.22 (dq, J=10.4, 1.5 Hz, 1H), 3.99 (dt, J=5.2, 1.6 Hz, 2H), 3.77 (s, 3H), 3.79-3.76 (m, 2H), 3.70-3.56 (m, J=7.4 Hz, 2H), 3.33 (br. s., 2H), 2.50 (s, 3H), 1.97-1.89 (m, 2H), 1.87-1.78 (m, J=9.3 Hz, 2H), 1.32 (s, 3H). LCMS (M+1)=437.20.

Provenance & Evidence