5-Chloro-2-fluoro-N-[4-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-phenyl]-benzenesulfonamide (709 mg) was added to a reaction vessel containing a magnetic stirring bar together with 3,5-dichloro-pyrazine-2-carbonitrile (300 mg), 1,1′-bis(diphenylphosphino)ferrocene-palladium(II) dichloride (Pd(dppf)2Cl2) (100 mg) and cesium carbonate (1.69 g), followed by 6 ml dioxane and 1 ml water, and the mixture heated to 100° C. under stirring. After 3 h the reaction mixture was cooled to RT and quenched with a saturated aqueous sodium bicarbonate solution (40 ml) and extracted with EtOAc (3×80 ml). The combined aqueous phases were dried over sodium sulfate, filtered and evaporated to afford the crude product as a brown oil. Purification by flash chromatography on silica gel using a mixture of EtOAc and heptane as the eluent afforded 5-chloro-N-[4-(6-chloro-5-cyano-pyrazin-2-yl)-phenyl]-2-fluoro-benzenesulfonamide as a brown foam after evaporation of the solvents under reduced pressure. Yield: 160 mg (22%).
