反应详情

To a solution of 6-bromo-5-fluoro-2-picolinic acid (2 g, 9.09 mmol) in tert-butanol (46 mL) and triethylamine (1.27 mL, 9.09 mmol, Eq: 1.00) was added DPPA (1.97 mL, 9.09 mmol). The slurry was stirred at room temperature until all solids dissolved (˜15 min), after which it was heated to 85° C. for 2 h. Upon cooling the mixture was concentrated onto silica gel and chromatographed (silica, 5% to 30% EtOAc in hexanes) to give slightly impure (6-bromo-5-fluoro-pyridin-2-yl)-carbamic acid tert-butyl ester (1.55 g, 59%). 1H NMR (400 MHz, CHLOROFORM-d6) δ ppm 7.97 (d, J=8.6 Hz, 1H), 7.43 (d, J=8.6 Hz, 1H), 1.53 (s, 9H).

1. dissolutiondissolved (˜15 min)
2. temperatureafter which it was heated to 85° C. for 2 h
3. temperatureUpon cooling the mixture
4. concentrationwas concentrated onto silica gel
5. customchromatographed (silica, 5% to 30% EtOAc in hexanes)