0.4 mmol 6-chloro-1-isoindolinone (CAS: 58083-59-3) was dissolved in 3 ml of pyridine. 0.05 mmol of 4-dimethylaminopyridine was added, followed by slow addition of a solution of 0.5 mmol 2-isopropoxy-5-methanesulfonyl-benzoyl chloride (prepared from example B1 and oxalyl chloride in dichloromethane) in 2 ml dichloromethane at room temperature. The reaction mixture is stirred for 10 minutes at room temperature, then the dichloromethane is stripped off in the rotatory evaporator. The remaining solution was then refluxed for 3 hours. The dark red solution was quenched with water, acidified by addition of diluted hydrochloric acid and extracted 3 times with ethyl acetate. The organic phase is dried and concentrated. Chromatography (silica gel; ethyl acetate/heptane) gave the title compound as a slightly yellowish solid. Yield=55%. MS (m/e): 408.2 [M+H]+, 100%).
