Trimethyl borate → HCID 68670785、化合物

To a stirring solution of 23 mL of n-BuLi (1.6 M in hexanes) in 20 mL of THF at −78° C. was added 5.31 g of 1,3-dibromo-5-(dimethoxymethyl)benzene in 80 mL of THF dropwise over a period of about 55 min. After 50 min., 3.2 mL (28.7 mmol) of B(OMe)3 was added, and the solution was stirred at −78° C. for 20 min. The cold bath was removed and stirring continued with gradual warming to r.t. After 1 h, 1 N HCl (45 mL) was added, and the aqueous layer was extracted with EtOAc. The extract was washed with brine, dried over Na2SO4, filtered, and concentrated. To a stirring mixture of crude product in 70 mL of 1N NaOH at 0° C. was added 14.5 mL of H2O2 (30 wt % in H2O) dropwise. After 25 min., 5 N HCl was added to a pH=1, and EtOAc and H2O were added. The organic layer was washed with brine, dried over Na2SO4, filtered, and concentrated. Purification by flash silica gel chromatography (15% EtOAc/hexanes) provided 1.92 g of 3-bromo-5-(dimethoxymethyl)phenol as a pale yellow solid with some impurity.