Trimethyl borate → (5-Ethoxy-2-fluoro-4-methoxyphenyl)boronic acid

Participants

Reaction Conditions

Reaction Steps

To a solution of 64D (324 mg, 1.1 mmol) in THF (5 mL) at −78° C. was slowly added n-BuLi (1.6 M in hexanes, 1.40 mL, 2.2 mmol). The reaction mixture was stirred at −78° C. for 20 min, followed by addition of trimethyl borate (0.31 mL, 2.8 mmol). The mixture was stirred at −78° C. for 3.0 h and then warmed up to rt over 18 h. It was quenched by addition of 1.0 N HCl (2.0 mL). After extraction with EtOAc, washing with a solution of Na2S2O3, brine and drying over Na2SO4, the crude product was purified by silica gel chromatography (eluting with 5% methanol in CH2Cl2) to give 64E (210 mg, 80% yield) as a white solid. 1H NMR (400 MHz, Methanol-d4) δ ppm 1.36 (t, J=6.81 Hz, 3H) 3.86 (s, 3H) 4.00 (q, J=7.03 Hz, 2H) 6.72 (d, J=10.11 Hz, 1H) 6.89 (d, J=5.27 Hz, 1H).

Provenance & Evidence