Tetrahydrofuran → 1,4-dimethyl-5-(tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole

Participants

Reaction Steps

A solution of 1,4-dimethyl-1H-pyrazole (480.0 mg, 4.993 mol) in tetrahydrofuran (20 mL, 300 mmol) at 0° C. was added 1.6 M n-butyllithium in hexane (4.7 mL, 7.5 mmol). The solution was stirred at room temperature for 1 h and then cooled to −78° C. To the solution was added 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (1.63 mL, 7.99 mmol). The reaction mixture was stirred at −78° C. for 0.5 h, then warmed up to 0° C. (taking 0.5 h). The reaction was quenched with brine and extracted with EtOAc (3×). The combined organic phases were washed with brine, dried over Na2SO4, and concentrated under reduced pressure. The residue was purified by combi-flash chromatography and eluted with EtOAc/hexane (0-60%). The purification gave 142 mg of product as white solid.

Provenance & Evidence