[Cl:1][C:2]1[CH:11]=[C:10]2[C:5]([N:6]=[C:7]([CH3:13])[C:8](=O)[NH:9]2)=[CH:4][CH:3]=1.[Cl:14][C:15]1[CH:16]=[C:17]2[C:22](=[CH:23][CH:24]=1)[NH:21][C:20](=O)[C:19]([CH3:26])=[N:18]2.P(Br)(Br)([Br:29])=O.[OH-].[NH4+]>CN(C)C=O>[Br:29][C:8]1[C:7]([CH3:13])=[N:6][C:5]2[C:10]([N:9]=1)=[CH:11][C:2]([Cl:1])=[CH:3][CH:4]=2.[Br:29][C:20]1[C:19]([CH3:26])=[N:18][C:17]2[C:22](=[CH:23][CH:24]=[C:15]([Cl:14])[CH:16]=2)[N:21]=1
6-Chloro-3-methylquinoxalin-2(1H)-one compound with 7-chloro-3-methylquinoxalin-2(1H)-one (300 mg, 771 μmol, Eq: 1.00) was stirred neat in phosphoryl tribromide (1.6 g, 5.58 mmol, Eq: 7.24). N,N-Dimethylformamide (1 drop) (771 μmol, Eq: 1.00) was added and the mixture was stirred at 105° C. for 1.5 h. The mixture was added to ice water and neutralized with aqueous 25% ammonium hydroxide. The precipitated solid was filtered and dried under high vacuum followed by preparative HPLC to give 3-Bromo-6-chloro-2-methyl-quinoxaline with 2-bromo-6-chloro-3-methyl-quinoxaline (40 mg, 10.1%) as a light brown solid. MS: m/z=195.03 (M+H+)
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