221352-10-9

To a solution of 2-(2-bromo-phenyl)-propane-2-ol (4.0 g, 18.6 mmol) in anhydrous THF (60 mL) under argon was slowly added n-butyl lithium (15 mL, 2.5 M). The mixture was stirred at -78° C for 2 h, and then triisopropylborate (5.5 mL, 24.2 mmol) was added to the mixture. The mixture was heated to room temperature and stirred for 12 h and then cooled to 0° C. Hydrochloric acid (10 mL, 1N) was added to the mixture until pH<5. The reaction system was then stirred at RT for 1 h. Until the solution was separated, the aqueous layer was extracted twice with ethyl acetate. The organic layers were combined, dried with anhydrous sodium sulfate, and filtered. The filtrate was concentrated under reduced pressure to afford a yellow oil. The oil was purified by chromatography (silica, EtOAc: hexanes,1:3) to afford 3,3-diMethylbenzo[c][1,2]oxaborol-1(3H)-ol which is a white solid.

[1] Patent: US2007/259936, 2007, A1. Location in patent: Page/Page column 168
[2] Patent: WO2011/19618, 2011, A1. Location in patent: Page/Page column 137-138
[3] Patent: US2007/259936, 2007, A1. Location in patent: Page/Page column 172
[4] Organic Process Research and Development, 2015, vol. 19, # 11, p. 1774 - 1783
[5] Patent: WO2012/109164, 2012, A1. Location in patent: Page/Page column 62-63