To a mixture of 2-(3-bromo-phenyl)-6-chloro-3,3-dimethyl-1,2,3,4-tetrahydro-quinoline-8-carboxylic acid methyl ester (410 mg, 1 mmol), palladium acetate (6.73 mg, 0.03 mmol), cesium carbonate (0.65 g, 2 mmol), xantphos (23 mg, 0.04 mmol) and 1-(ortho-tolyl)piperazine hydrochloride (320 mg, 1.5 mmol) in toluene (10 mL) was stirred at 120° C. for 12 hours. Then the reaction mixture was concentrated in vacuo and the residue was extracted with ethyl acetate (2×100 mL), washed with saturated aqueous sodium chloride (2×50 mL), 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) (20% ethyl acetate/hexanes) to afford 3,3-dimethyl-2-[3-(4-o-tolyl-piperazin-1-yl)-phenyl]-1,2,3,4-tetrahydro-quinoline-8-carboxylic acid methyl ester (0.10 g, 21%) as a white solid: LC/MS m/e calcd for C30H35N3O2 (M+H)+: 470.6, observed: 470.6.
