Trimethyl borate → 3,3-diethyl-5-methylbenzo[c][1,2]oxaborol-1(3H)-ol

Participants

Reaction Steps

To a solution of 3-(2-bromo-5-methylphenyl)pentan-3-ol (6.5 g, 25.2 mmol) in THF (150 ml) at −78° C. was slowly added n-BuLi (30.24 ml, 75.6 mmol). The reaction mixture was warmed to rt and stirred for 2 h. After being cooled to −78° C., trimethyl borate (5.23 g, 50.4 mmol) was added dropwise and the reaction mixture was warmed to rt, stirred for 10 h under nitrogen and quenched with 2N HCl (50 ml). The mixture was extracted with EA (40 ml×3). The combined organic layers were washed with water and brine, dried over Na2SO4, filtered and concentrated under reduced pressure. The residue was purified by column chromatography over silica gel eluted with PE:EA (10:1 to 1:1) to give the product (2.0 g, yield 38.9%) as a white solid. 1H NMR (300 MHz, DMSO-d6): δ 8.87 (s, 1H), 7.52-7.47 (d, 1H), 7.11-7.06 (m, 2H), 2.35 (s, 3H), 1.88-1.68 (m, 4H), 0.60-0.45 (m, 6H). MS: m/z=205 [M+1]+.

Provenance & Evidence