A mixture of 6-(4-hydroxy-2-methoxyphenyl)-5-(2-methoxyphenylaminomethyl)-2,2,4-trimethyl-1,2-dihydroquinoline (Reference Compound No. 4-1, 25.0 mg, mmol), 2-methylnicotinoic acid (8.0 mg, 0.058 mmol), N,N-diisopropylethylamine (20.2 μL, 0.116 mmol) and O-(7-azabenzotriazol-1-yl)-N,N,N,N-tetramethyluronium hexafluorophosphate (24.3 mg, mmol) was dissolved in anhydrous N,N-dimethylformamide (0.5 mL), and then the reaction mixture was stirred at room temperature overnight. The reaction mixture was diluted with ethyl acetate (70 mL). The mixture was washed with water (70 mL) and saturated brine (50 mL) successively, dried over anhydrous magnesium sulfate, and then the solvent was removed under reduced pressure. The obtained residue was purified by silica gel column chromatography (hexane-ethyl acetate) to give the titled compound (20.7 mg) as a colorless solid. (Yield 65%)
