A stirred suspension of 421 (500 mg, 2 mmol), 3,4-difluoronitrobenzene (795 mg, 5 mmol) and cesium carbonate (1.63 g, 5 mmol) in anhydrous DMF (50 ml) was heated at 85° C. under nitrogen for 7 hrs. It was then cooled down to room temperature poured in water, and extracted with dichloromethane. The combined organic extracts was concentrated and purified twice by flash column chromatography (eluents 2% of NH4OH in methanol/CH2Cl2: 5/95 to 10/90) to afford title compound 422 (144 mg, 19% yield) as a sticky yellow solid. LCMS: 384.0 (M+H)+.
