Ethylene carbonate → 2-(4-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazol-1-yl)ethan-1-ol

Participants

Reaction Steps

4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole (9.66 g, 49.8 mmol), 1,3-dioxolan-2-one (21 g, 238 mmol) and cesium carbonate (16 g, 49.1 mmol) were combined in a 100 mL round bottom flask. The reaction mixture was warmed from room temperature to 100° C. in an oil bath, by which time the carbonate had melted and served as the solvent for the reaction, which remained a slurry. After heating for 3.5 hours, the reaction mixture was cooled to room temperature and diluted with ethyl acetate, then filtered through Celite washing repeatedly with ethyl acetate. The filtrate was concentrated, then purified by chromatography on an Analogix(R) Intelliflash™ purification system using a SF60-200 g column at a flow rate of 80 mL/minutes, eluting as follows: 5 minutes at 20% ethyl acetate/hexanes, then ramped from 40% to 90% ethyl acetate/hexanes over 35 minutes, then 100% ethyl acetate for another 20 minutes, to provide the title compound. MS (ESI+) m/z 239.0 (M+H)+.

Provenance & Evidence