Boron trifluoride etherate → 6-bromo-2-(4-tert-butoxycarbonylbenzyl)-1-oxo-4-phenyl-1,2-dihydroisoquinoline-3-carboxylic Acid Methyl Ester

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Reaction Steps

To a solution of 6-bromo-2-(4-carboxybenzyl)-1-oxo-4-phenyl-1,2-dihydroisoquinoline-3-carboxylic acid methyl ester (300 mg) and 2,2,2-trichloroacetoimidate tert-butyl ester (400 mg) in methylene chloride (6 ml) was added dropwise a catalytic amount of boron trifluoride diethyl etherate at room temperature and the mixture was stirred for 1 hr. To the reaction mixture was added 10% aqueous potassium carbonate solution, and the mixture was concentrated under reduced pressure and extracted with ethyl acetate. The organic layer was washed with water and saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residue was purified by basic silica gel column chromatography (ethyl acetate) and the obtained crystals were washed with methanol to give the title compound (260 mg).

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