A mixture of 2-benzyl-6-bromo-1-oxo-4-phenyl-1,2-dihydroisoquinoline-3-carboxylic acid methyl ester (300 mg), methylboronic acid (200 mg), tetrakis(triphenylphosphine)palladium(0) (80 mg), potassium carbonate (280 mg), toluene (6 ml) and THF (3 ml) was stirred at 100° C. under a nitrogen atmosphere for 12 hrs. Water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer was washed with water and saturated brine. The solvent was dried over anhydrous sodium sulfate and the residue was concentrated under reduced pressure. The obtained residue was purified by silica gel column chromatography (hexane-hexane:ethyl acetate=2:1) and recrystallized (ethyl acetate-hexane) to give the title compound (210 mg).
