Under nitrogen were added 2.40 mL (48 mmol) of a 2 mol/L aqueous sodium carbonate solution and 729.9 mg (0.632 mmol) of tetrakis(triphenylphosphine)palladium (0) to a solution of 4.50 g (7.79 mmol) of 1,3-bis[4-(4-bromobenzoyl)-1-piperazinyl]propane and 4.50 g (18.7 mmol) of 4-isopropoxy-3,5-dimethoxyphenylboronic acid in ethanol-toluene (15 mL -60 mL), and the mixture was stirred for 3 hours at 80° C. The reaction mixture was concentrated under reduced pressure to remove the organic solvents. Water (15 mL) was added to the residue and the mixture was extracted with chloroform (100 mL, 3×30 mL). The organic layers were combined, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residue was purified by chromatography on silica gel to give 5.93 g of 1,3-bis[4-[4-(4-isopropoxy-3,5-dimethoxyphenyl)benzoyl]-1-piperazinyl]propane as a colorless oil (yield 94%).
