Benzenesulfonamide, 3-amino- → 3-(Pyrazin-2-ylamino)benzenesulfonamide

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A mixture of 3-aminobenzenesulfonamide (130mg, 0.75 mmol), 2-chloropyrazine (0.067 mL, 0.75 mmol),(9,9-dimethyl-9H-xanthene-4,5-diyl)bis(diphenylphosphine) (34.9 mg, 0.06 mmol), diacetoxypalladium (6.78 mg, 0.03 mmol) and cesium carbonate (295 mg, 0.91 mmol) in degassed DMA (2.1 mL) was heated **_in the microwave_** for 15 min at 130 °C. LC MS FLA-04665-01-01 (pH extract 6-7) showed some product and few sulfanilamide left. Reaction was stopped. Extraction with AE + ethanol / aq. sat NH4Cl (pH7), then back extraction with DCM.The organics were dried over MgSO4 and concentrated _in vacuo._ The crude product was adsorbed on silica gel 40-60µm and purified by flash chromatography on silica gel 15-40µm eluting with 3.5 % of ethanol in dichloromethane (NH3 0.5 %) to provide 3-(pyrazin-2-ylamino)benzenesulfonamide (80 mg, 42.3 %) as a colourless solid. 1H NMR, LC MS FLA-04665-09-02: OK

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