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

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Reaction Conditions

Reaction Steps

4-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole (1.00 g, 5.15 mmol) and cesium carbonate (5.04 g, 15.47 mmol) were suspended in 10 mL of dimethylformamide. 2-Bromoethanol (0.73 mL, 10.30 mmol) was added and the mixture was stirred at 70° C. for 3 hours. Additional amounts of cesium carbonate (5.04 g, 15.47 mmol) and 2-bromoethanol (0.73 mL, 10.30 mmol) were added and the mixture was left at 70° C. overnight. The solvent was evaporated under reduced pressure and the residue was partitioned between water and ethyl acetate. The organic layer was washed with water and brine, dried over magnesium sulphate, filtered and the solvent was evaporated to give 770 mg (63% yield) of a yellowish oil that was used in the next step without further purification.

Provenance & Evidence