A mixture of 2-(3-amino-phenyl)-3,3-dimethyl-1,2,3,4-tetrahydro-quinoline-6-carbonitrile (0.64 g, 2.3 mmol), 2-bromo-2-methyl-propionic acid methyl ester (1.25 g, 6.9 mmol) and potassium carbonate (1.59 g, 11.5 mmol) in N,N-dimethylformamide (6 mL) was stirred at 25° C. for 5 d. Then the reaction mixture was extracted with ethyl acetate (2×100 mL), washed with water, dried over anhydrous sodium sulfate and concentrated in vacuo. Purification on flash silica gel chromatography (silica gel from QingDao, 200-300 mesh, glass column from Shanghai SD company) (30% ethyl acetate/hexanes) to afford 2-[3-(6-cyano-3,3-dimethyl-1,2,3,4-tetrahydro-quinolin-2-yl)-phenylamino]-2-methyl-propionic acid methyl ester (500 mg, 43%) as a brown oil: LC/MS m/e calcd for C23H27N3O2 (M+H)+: 378.49, observed: 378.2.
