Sodium Hydroxide → 4-Cyclohexyloxy-benzeneboronic acid

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Reaction Steps

n-Butyllithium (1.6 M in hexane) (136 mL) was dropwised to a mixture of 1-bromo-4-(cyclohexyloxy)benzene (46.3 g) and THF (dry) (500 mL) at −78° C. and the mixture was stirred at the same temperature under nitrogen for 40 min. Triisopropyl borate (51.2 g) was dropwised to the mixture at −78° C. for 15 min and the mixture was stirred at the same temperature for 5 min. Then the mixture was warmed up to room temperature and stirred for additional 30 min. The mixture was poured into 1N NaOH aq. (250 mL) and water (750 mL) and the mixture was further stirred for 30 min. The organic layer was separated and the aqueous phase was washed with Et2O (300 mL×2) and acidified by 6N HCl aq. The mixture was extracted with EtOAc, dried over anhydrous sodium sulfate and concentrated in vacuo to give 4-(cyclohexyloxy)phenylboronic acid (29.5 g) as a white powder. Tetrakis(triphenylphosphine)palladium(0) (0.656 g) was added to a suspension of 3-bromopyridin-2-amine (9.83 g), 4-(cyclohexyloxy)phenylboronic acid (15.0 g) and sodium carbonate (12.0 g) in DME (325 mL) and water (65.0 mL) and the mixture was stirred at 100° C. under nitrogen for 3 hr and at 90° C. for 12 hr. Volatiles were removed in vacuo with silica-gel. The silica-supported mixture was purified by column chromatography (silica gel, eluted with EtOAc in hexane) to give the title compound (14.1 g) as a white powder.

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