Diethyl Ether → 4,4,5,5-Tetramethyl-2-(4-(trifluoromethyl)phenyl)-1,3,2-dioxaborolane

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Reaction Steps

4-bromobenzotrifluoride (4.8 g, 21.3 mmol) was placed in a reaction flask. To ensure a nitrogen atmosphere in the reaction flask, the gas in the reaction flask was drawn out and the reaction flask was refilled with nitrogen gas in a rapid manner three times. To the reaction flask, 50 ml of anhydrous diethylether was added, and then 10 ml of n-butyllithium solution (25.6 mmol, 2.5 M in n-hexane) was slowly added at −78° C. to obtain a mixture. In the meanwhile, the color of the mixture changed from transparent to cloudy green. The mixture was kept at −78° C. and continuously stirred for 60 minutes. Next, 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (5.2 ml, 25.6 mmol) was slowly added to the mixture at −78° C., and then the temperature was slowly raised to and kept at 20° C. for 12 hours for reaction. The color of the mixture in the reaction flask changed from cloudy green to cloudy white. Deionized water was slowly added to the mixture to terminate the reaction in the reaction flask. The solvents in the mixture were drawn out of the reaction flask, and the residue in the reaction flask was washed several times with ethyl acetate and with a saturated sodium chloride solution to collect an organic layer, followed by dehydration of the organic layer using sodium sulfate (Na2SO4) to thereby obtain a crude product. The crude product was recrystallized in a mixed solvent having dichloromethane and n-hexane (dichloromethane:n-hexane=1:1) at 20° C., thereby obtaining white crystals (4.27 g, 73% yield).

Provenance & Evidence