Hydrochloric Acid → 2-(2,2,2-Trifluoro-ethoxy)-3,5-di-tert-butylphenyl-boronic acid

Participants

Reaction Conditions

Reaction Steps

1,5-Di-tert-butyl-3-iodo-2-(2,2,2-trifluoro-ethoxy)-benzene (3.17 g, 7.7 mmol) was dissolved in anhydrous diethyl ether (75 mL) in an oven-dried flask under nitrogen. N,N,N′,N′-Tetramethyl ethylenediamine (1.73 mL, 11.5 mmol) was added and the reaction cooled in a dry ice/acetone bath. At −76° C. to −73° C. was added over 5 min n-butyl lithium (4.6 mL, 11.5 mmol, 2.5M in hexane). The reaction was stirred at −75° C. for 15 min and then treated slowly with trimethyl borate (2.6 mL, 23 mmol). The reaction was stirred at −75° C. for 1 h. The dry ice/acetone bath was replace with an ice bath and the reaction was allowed to warm to 0° C. over 40 min. 1N hydrochloric acid (50 mL) was added and after 5 min the ice bath was removed and stirring allowed to continue for 1 h. The aqueous and organic layers were separated and the aqueous layer was washed with ethyl acetate (2×75 mL). The combined organic portion was washed with brine (100 mL), dried (MgSO4), filtered and evaporated in vacuo to provide a yellow gum. The material was purified by flash chromatography using (9:1) hexane:ethyl acetate and then (4:1) hexane:ethyl acetate to give 1.28 g (50%) of an off-white solid.

Provenance & Evidence