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 At room temperature all reagents were solids. The reaction was warmed from room temperature to 100° C. in an oil bath, at which time the carbonate had melted and served as the solvent for the reaction, which then remained a slurry. After heating for 3.5 hours, the reaction was cooled to room temperature, diluted with ethyl acetate, and filtered through Celite® (diatomaceous earth) washing repeatedly with ethyl acetate. The filtrate was concentrated, and the residue was purified by chromatography on an Analogix® Intelliflash™ purification system using a SF60-200 g column at a flow rate of 80 mL/minute, eluting as follows: 5 minutes at 20% ethyl acetate/hexane, then ramped from 40% to 90% ethyl acetate/hexanes over 35 minutes, and then 100% ethyl acetate for another 20 minutes, to afford the title compound.

Provenance & Evidence