Hydrochloric Acid → Ethyl 7-(4-tert-butylphenyl)-2,3-dihydro-1-benzoxepine-4-carboxylate

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Reaction Steps

Under argon atmosphere, to a solution of 4-tert-butylbromobenzene (10.0 g) in diethylether (50 ml) was added n-butyllithium (1.6M, hexane solution) (32.3 ml) at −78° C., and the mixture was stirred for 1 hour. To the reaction mixture was dropwise added trimethyl boric acid (16 ml) in diethylether (30 ml), and the mixture was warmed to room temperature and stirred at room temperature 16 hours. To the reaction mixture were added 1N hydrochloric acid (50 ml) and water, and the mixture was extracted with ethyl acetate. The organic layer was washed with saturated sodium chloride solution, dried with magnesium sulfate and concentrated under reduced pressure. The residue was separated and purified with column chromatography (ethyl acetate/hexane=1:9) to give crude 4-tert-phenyl borate (0.84 g) as pale yellow oil. Under argon atmosphere, a solution of ethyl 7-bromo-2,3-dihydro-1-benzoxepine-4-carboxylate (500 mg), the above crude 4-tert-butylphenyl borate (0.59 g) and potassium carbonate (0.47 g) in toluene-ethanol-water (20-2-2 ml) was stirred at room temperature for 1 hour. To the reaction mixture was added tetrakistriphenylphosphine palladium (0.06 g), and the mixture was refluxed for 20 hours and cooled to room temperature. The organic layer was washed with saturated sodium chloride solution, dried with magnesium sulfate and concentrated under reduced pressure. The residue was separated and purified with column chromatography (ethyl acetate/hexane=1:19) to give ethyl 7-(4-tert-butyl-phenyl)-2,3-dihydro-1-benzoxepine-4-carboxylate (504 mg) as colorless oil.

Provenance & Evidence