Trimethyl borate → (4-(2-((tert-Butyldimethylsilyl)oxy)-1,1-difluoroethyl)-3,5-dimethylphenyl)boronic acid

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Reaction Steps

n-BuLi (1.6 M in hexanes, 1.236 ml, 1.977 mmol) was added to a solution of Intermediate 7C (500 mg, 1.318 mmol) in THF (5 ml) at −78° C. After 45 min, trimethyl borate (0.295 ml, 2.64 mmol) was added and the cooling bath was removed. The reaction mixture was warmed to rt, diluted with diethyl ether (300 mL), washed with 1.0 HCl, water and brine and concentrated. The crude product was purified by flash chromatography (loading in chloroform, 0 to 100% ethyl acetate in hexane over 30 min using a 12 g Isco column). Intermediate 7D (370 mg, 82% yield) was obtained as a white solid. 1H NMR (400 MHz, chloroform-d) δ ppm −0.03-0.02 (m, 6H) 0.82-0.88 (m, 9H) 2.57-2.63 (m, 6H) 4.10 (t, J=12.92 Hz, 2H) 7.86 (s, 2H).

Provenance & Evidence