Br[C:2]1[CH:3]=[CH:4][C:5]([C:8]([CH3:11])([CH3:10])[CH3:9])=[N:6][CH:7]=1.C([O:15][B:16](OC(C)C)[O:17]C(C)C)(C)C.C([Li])CCC.CCCCCC>O1CCCC1.CCOCC>[C:8]([C:5]1[CH:4]=[CH:3][C:2]([B:16]([OH:17])[OH:15])=[CH:7][N:6]=1)([CH3:11])([CH3:10])[CH3:9]
To a solution of 5-bromo-2-(tert-butyl)pyridine (1 g, 4.67 mmol) and triisopropylborate (1.29 mL, 5.60 mmol) in anhydrous tetrahydrofuran (10 mL) at −78° C. under nitrogen was added dropwise a solution of n-butyl lithium in hexane (2.5 M, 2.06 mL, 5.14 mmol). The reaction was stirred at −78° C. for 2½ hours then allowed to warm slowly to −10° C. over 1 hour. The reaction was quenched by the addition of water (10 mL) and the tetrahydrofuran removed under reduced pressure. The resulting aqueous suspension was diluted with water (30 mL) and washed with ether (30 mL). The aqueous phase was acidified to pH 6 by the addition of acetic acid and the resulting milky suspension extracted with ether (2×20 mL). The combined organic extracts were washed with saturated brine (2×50 mL), dried (MgSO4), filtered and concentrated under reduced pressure to give a white foam. Ether (5 mL) and hexanes (40 mL) were added and the resulting suspension stirred vigorously for 30 minutes then filtered to give 2-(tert-butyl)pyridine-5-boronic acid (0.5093 g, 61% yield) as a white solid.
Wird geladen…
