[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([S:8]([NH2:11])(=[O:10])=[O:9])=[CH:4][CH:3]=1.C(=O)([O-])[O-].[K+].[K+].[Cl:18][C:19]1[C:28](Cl)=[N:27][C:26]2[C:21](=[CH:22][CH:23]=[CH:24][CH:25]=2)[N:20]=1.N#N>CN(C=O)C>[Cl:1][C:2]1[CH:3]=[CH:4][C:5]([S:8]([NH:11][C:28]2[C:19]([Cl:18])=[N:20][C:21]3[C:26](=[CH:25][CH:24]=[CH:23][CH:22]=3)[N:27]=2)(=[O:9])=[O:10])=[CH:6][CH:7]=1To a solution of 4-Chlorobenzenesulfonamide (1.92 g, 10 mmol) in anhydrous DMF (50 mL) was added solid potassium carbonate (1.38 g, 10 mmol) in one portion. The reaction mixture was stirred for 10 minutes, followed by the addition of 2,3-dichloroquinoxaline (1.99 g, 10 mmol). Heating the resultant mixture under refux conditions in an atmosphere of N2 for 2.5 h gave the desired product. The progress of the reaction was monitored by TLC using, hexanes/EtOAc 3:1. After cooling the reaction mixture is slowly added to a vigorously stirred aqueous solution of AcOH (1%, 500 mL). The desired product precipitates as grey crystals, which are filtered and dried overnight in desiccator. Yield 2.32 g, 66%; Rf=0.7 (hexanes/EtOAc 1:1); HPLC/MS: [M+H]+ m/z 354. 1H NMR: (DMSO-d6, 600 MHz) 7.68 (t, J=7.8 Hz, 1H), 7.72 (d, J=8.4 Hz, 2H), 7.78 (td, J=7.8 Hz, J=1.2 Hz, 1H), 7.89 (d, J=8.4 Hz, 2H), 8.19 (d, J=8.4 Hz, 2H).
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