C[O:2][C:3]([C:5]1[CH:10]=[N:9][CH:8]=[CH:7][N:6]=1)=O.O.[NH2:12][NH2:13]>CCO>[N:6]1[CH:7]=[CH:8][N:9]=[CH:10][C:5]=1[C:3]([NH:12][NH2:13])=[O:2]To a stirred solution of pyrazine-2-carboxylic acid methyl ester (11.1 g, 80 mmol) in 140 mL of EtOH was added hydrazine hydrate (15.6 mL, 320 mmol). The resultant solution was heated to reflux for 2 h. The solvent was removed under reduced pressure and dried under high vacuum to yield the title amide (11.1 g, 100%) as a white solid. The product was used in subsequent steps without purification. 1H NMR (d6-DMSO δ 10.1, br s, 1H; δ 9.12, d, 1H; δ 8.83, d, 1H; δ 8.70, dd, 1H; δ 4.64, br s, 2H), LC/MS (APCI, ES, M+H=139).
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