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

Participants

Reaction Conditions

Reaction Steps

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).

Provenance & Evidence