Iodine → (3-tert-Butylphenyl)boronic acid

Participants

Reaction Steps

To a solution of dry THF (10 mL) was added magnesium (1.25 g, 52 mmol), 3-t-butyl bromobenzene (2.0 g, 9.4 mmol) and a crystal of iodine. The reaction was first heated slightly until the reaction started and then removed. The remaining 3-t-butyl bromobenzene (8.0 g, 37.7 mmol) was added via an addition funnel until the spontaneous refluxing stopped. The reaction mixture was heated to reflux for 2 hours. The Grignard was transferred via a syringe into a cooled solution (−40° C.) of trimethyl borate dissolved in THF and added over a 10 minute period. The reaction mixture was warmed to room temperature overnight. Ethyl acetate and distilled water were added to the reaction mixture and the layers separated. The organics were washed with brine and dried over magnesium sulfate. The solvent was concentrated and the product purified by a silica gel column using 10% ethyl acetate and hexanes as the eluants to give 3-t-butylphenyl boronic acid (4.0 g, 46% yield) as a white solid. The product was confirmed by GCMS and was used directly in the next step.

Provenance & Evidence