1379338-74-5

2,6-Dichloro-3,4-pyridinediamine (7.85 g, 0.044 mol) and 40% aqueous glyoxal (26 g, 0.178 mol) were mixed in ethanol and the reaction was carried out at reflux overnight. After completion of the reaction, the mixture was cooled to room temperature, the precipitate was collected, washed with ethanol and dried under vacuum to give 5,7-dichloropyrido[3,4-b]pyrazine (7.32 g, 83% yield).

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[5] Patent: US2014/5188, 2014, A1. Location in patent: Paragraph 0562; 0563; 0564