Triisopropyl borate → (R)-(2-Fluoro-4-(1-hydroxypropan-2-yl)-5-methoxyphenyl)boronic acid

Temperature

-78 °C

To a solution of 25B (1.12 g, 3.75 mmol) in THF (20 mL) was dropwise added sec-butyllithium (3.22 mL, 4.50 mmol) at −78° C. and stirred at −78° C. for 10 min. Triisopropyl borate (1.743 mL, 7.50 mmol) was added and the mixture was slowly warmed up to r.t. overnight. The reaction was quenched by 6.0 ml of 1N HCl and the mixture was stirred at r.t. for 4 h. TBS is ˜60% removed. Addition 4 ml of 1 N HCl was gassed and the mixture was heated at 50° C. for 1 h. The mixture was concentrated and purified by prep HPLC to yield 25C (700 mg, 3.07 mmol, 82% yield) as a white solid. MS (ESI) m/z: 227.5 (M−H)+. 1H NMR (400 MHz, methanol-d3) δ ppm 6.87-6.94 (2H, m), 3.81 (3H, s), 3.70 (1H, dd, J=10.77, 5.93 Hz), 3.51 (1H, dd, J=10.55, 7.47 Hz), 3.32-3.37 (1H, m), 1.22 (3H, d, J=7.03 Hz).

1. customat −78° C.
2. temperaturethe mixture was slowly warmed up to r.t. overnight
3. customThe reaction was quenched by 6.0 ml of 1N HCl
4. stirringthe mixture was stirred at r.t. for 4 h
5. customremoved
6. additionAddition 4 ml of 1 N HCl
7. temperaturethe mixture was heated at 50° C. for 1 h
8. concentrationThe mixture was concentrated
9. custompurified by prep HPLC

ORD record

ord-0dba43f0779c442e9c4cda021be26654

Source dataset

uspto-grants-2015_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09174974B2