Reaction Steps
To a stirred solution of 1M KHMDS/THF (49.3 mL, 49.3 mmol) in THF (150 mL) at −78° C. was added dropwise a THF (100 mL) solution of ethyl 2-(7-(4-(allyloxy)-4-methylpiperidin-1-yl)-2-(3-bromophenyl)-5-methylpyrazolo[1,5-a]pyrimidin-6-yl)acetate (20 g, 37.9 mmol) over 5 min. After 30 min, a THF (100 mL) solution of 3-phenyl-2-(phenylsulfonyl)-1,2-oxaziridine (12.88 g, 49.3 mmol) was added and stirred for additional 30 min at −78° C. Then, the resulting dark reaction mixture was quenched with sat. NH4Cl (50 mL), diluted with EtOAc (200 mL), washed with water (100 mL), brine (100 mL), dried (Na2SO4), filtered and concentrated. The residue was then purified by Biotage(5-50% EtOAc/hexane) to afford ethyl 2-(7-(4-(allyloxy)-4-methylpiperidin-1-yl)-2-(3-bromophenyl)-5-methylpyrazolo[1,5-a]pyrimidin-6-yl)-2-hydroxyacetate (17 g, 31.3 mmol, 82% yield) as white foam. Impurities were present by NMR. Used as is in the next step without further purification. 1H NMR (500 MHz, CDCl3) δ 8.16 (t, J=1.7 Hz, 1H), 7.99-7.92 (m, 1H), 7.58-7.50 (m, 2H), 7.34 (t, J=7.9 Hz, 1H), 6.83 (s, 1H), 6.18-6.06 (m, 1H), 5.57 (d, J=5.4 Hz, 1H), 5.48 (d, J=17.0 Hz, 1H), 5.27 (d, J=10.2 Hz, 1H), 4.83 (br. s., 2H), 4.35 (dq, J=10.8, 7.1 Hz, 1H), 4.23 (dq, J=10.9, 7.1 Hz, 1H), 4.06-3.99 (m, 2H), 2.65 (s, 3H), 2.00 (d, J=14.2 Hz, 2H), 1.84 (d, J=13.4 Hz, 2H), 1.36 (s, 3H), 1.29-1.26 (m, 3H). LCMS (M+H)=545.3.
