Synthesis
General procedure for the synthesis of 3-aminopyrazine-2-carboxylic acid from methyl 3-aminopyrazine-2-carboxylate: Methyl 3-aminopyrazine-2-carboxylate (2.08 g, 13.6 mmol) was suspended in methanol (40 mL) under nitrogen protection, and treated with 1N aqueous sodium hydroxide (30 mL). The reaction mixture was warmed up to room temperature and stirred for 50 min. Subsequently, methanol (about 45 mL) was partially evaporated under reduced pressure. The resulting mixture was cooled in an ice water bath and 1N aqueous hydrochloric acid solution (70 mL) was slowly added. Initially the mixture appeared as a solution and gradually a precipitate was generated with further addition of acid. The solid product was collected by filtration, washed with water (3 x 10 mL) and finally dried under vacuum to give 1.48 g of the target product 3-aminopyrazine-2-carboxylic acid.
References
[1] Journal of Medicinal Chemistry, 2011, vol. 54, # 7, p. 2320 - 2330
[2] Patent: WO2013/169907, 2013, A1. Location in patent: Page/Page column 44