(S)-isopropyl 2-(5-bromo-4-(3,3-dimethylazetidin-1-yl)-2,6-dimethylpyridin-3-yl)-2-hydroxyacetate → (S)-isopropyl 2-(5-bromo-4-(3,3-dimethylazetidin-1-yl)-2,6-dimethylpyridin-3-yl)-2-(tert-butoxy)acetate

Participants

Reaction Steps

The isobutylene gas was bubbled into a nitrogen purged, cooled (0° C.) solution of (S)-isopropyl 2-(5-bromo-4-(3,3-dimethylazetidin-1-yl)-2,6-dimethylpyridin-3-yl)-2-hydroxyacetate (970 mg, 2.5 mmol) and 0.5 mL of 70% HClO4 in DCM (20 mL) for 20 min. The reaction mixture was allowed to warm to rt and stirred for 18 h in a pressure sealed vessel, diluted with DCM, washed with 1M Na2CO3 solution, and dried over MgSO4. The crude product was charged (DCM) to a 40 g ISCO silica gel cartridge and gradient elution (5-35% EtOAc/hexanes) using an Isolera chromatography station gave (S)-isopropyl 2-(5-bromo-4-(3,3-dimethylazetidin-1-yl)-2,6-dimethylpyridin-3-yl)-2-(tert-butoxy)acetate 578 mg (52%). 1H NMR (500 MHz, DMSO) δ 5.30 (s, 1H), 5.0-4.95 (m, 1H), 4.12 (d, J=7.2 Hz, 2H), 4.02 (br. s, 2H), 2.44 (s, 3H), 2.25 (br. s, 3H), 1.26 (s, 6H), 1.20 (d, J=6.3 Hz, 3H), 1.17 (d, J=6.3 Hz, 3H), 1.07 (s, 9H). UPLC (M+H)=443.3.

Provenance & Evidence