Synthesis
General procedure for the synthesis of 3-amino-5,6-dichloro-2-pyrazinecarboxylic acid from methyl 3-amino-5,6-dichloro-2-pyrazinecarboxylate: Referring to the preparation of Example 72 (Compound 207 in Table 1); a mixture of methyl 3-amino-5,6-dichloro-2-pyrazinecarboxylate (3.6 g, 16 mmol, Aldrich) and sodium hydroxide (1.6 g. 39 mmol) suspension in water (30 mL) was heated to reflux for 15 minutes. Upon completion of the reaction, the reaction mixture was filtered, cooled to room temperature and acidified with 1 N hydrochloric acid to pH < 7. The precipitated 3-amino-5,6-dichloro-pyrazine-2-carboxylic acid solid (1.2 g, 36% yield) was collected by filtration, dried in air and further dried under vacuum.
