Ethyl Acetate → (3E)-6-fluoro-3-[4-(2-fluoropyridin-4-yl)-5,5-dimethylfuran-2(5H)-ylidene]-1,3-dihydro-2H-indol-2-one

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To a mixture of (3E)-3-(4-bromo-5,5-dimethylfuran-2(5H)-ylidene)-6-fluoro-1,3-dihydro-2H-indol-2-one (2.0 g, 6.1 mmol), 2-fluoropyridine-4-boronic acid (1.1 g, 8.0 mmol), potassium fluoride (1.8 g, 5 eq.) in dioxane (50 mL) and water (5 mL) under a nitrogen atmosphere, was added [1,1′-bis(diphenylphosphino)ferrocene]dichloropalladium(II) (250 mg, 5%). The mixture was heated at 80° C. for 20 hour. The reaction was allowed to cool to room temperature and ethyl acetate (350 mL) was added. The organic phase was washed with water (100 mL×2) and evaporated to provide the crude product. The crude product was purified by column chromatography (silica gel, 5% CH3OH/CH2Cl2 elution) and then recrystallized from ethyl acetate/hexanes (80/20) to provide (3E)-6-fluoro-3-[4-(2-fluoropyridin-4-yl)-5,5-dimethylfuran-2(5H)-ylidene]-1,3-dihydro-2H-indol-2-one as a yellow-orange solid (1.2 g, yield 57%).

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