Benzyl Bromide → 1-Benzyl-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole

Participants

Reaction Conditions

Reaction Steps

Into a 100-mL three neck round-bottom flask, was placed a solution of 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole (3.60 g, 18.6 mmol) in THF (50 mL). Sodium hydride (742 mg, 18.6 mmol, 60% dispersion in mineral oil) was carefully added in portions at 0° C. The resulting mixture was stirred for 30 min at 0° C., then benzyl bromide (2.21 mL, 18.6 mmol) was added. The resulting mixture was stirred overnight at room temperature, then carefully quenched with water (10 mL). The pH of the mixture was adjusted to 9-10 with aqueous HCl (2 M) and the aqueous phase was extracted with EtOAc (300 mL). The combined organic layers were washed with brine (2×150 mL), dried (Na2SO4), filtered and concentrated under vacuum. The residue was purified by silica gel chromatography with ethyl acetate/petroleum ether (1/2) as eluent to yield the title compound as a yellow oil (3.47 g, 66%).

Provenance & Evidence