Trimethyl borate → 3-tert-butyl-5-bromophenol

Participants

Reaction Steps

To a stirring solution of 34 mL of 1.6 M n-BuLi in hexanes in 20 mL of THF at −78° C. was added 8.15 g of 1,3-dibromo-5-tert-butylbenzene in 80 mL of THF dropwise over a period of 1 h. After 1 h at −78° C., 4.6 mL of B(OMe)3 was added, and after 20 min. the cold bath was removed and stirring continued with warming to r.t. After 1 h, EtOAc and 70 mL of 1 N HCl were added, and the layers were separated. The organic layer was washed with brine, dried over Na2SO4, filtered, and concentrated. To a stirring mixture of the crude product in 105 mL of 1 N NaOH at 0° C. was added 22 mL of H2O2 (30 wt % in H2O) dropwise. After 25 min. 5 N HCl was added to a pH=1. Ethyl acetate was added, and the organic layer was washed with 80 mL of brine, dried over Na2SO4, filtered, and concentrated. Purification by flash silica gel chromatography (hexanes to 10% EtOAc/hexanes) provided 6.54 g of 3-bromo-5-tert-butylphenol as an orange oil with some impurity.

Provenance & Evidence