Synthesis
The general procedure for the synthesis of ethyl 2-amino-1H-imidazole-5-carboxylate from 2-aminopyrimidine and ethyl 3-bromopyruvate was as follows: to an ethanol solution (20 mL) containing ethyl imidazo[1,2-a]pyrimidine-2-carboxylate and ethyl imidazo[1,2-a]pyrimidine-3-carboxylate (500 mg, 2.62 mmol, 1.0 eq.), hydrazine hydrate ( 180 mg, 2.88 mmol, 1.1 equiv). The reaction mixture was heated and reacted at 75 °C overnight. After completion of the reaction, the reaction mixture was concentrated and the resulting residue was purified by silica gel column chromatography (eluent ratio dichloromethane/methanol = 20/1, v/v) to give ethyl 2-amino-1H-imidazole-4-carboxylate (220 mg, 54% yield) as a yellow solid.
References
[1] Journal of Medicinal Chemistry, 2010, vol. 53, # 15, p. 5620 - 5628
[2] Patent: WO2018/11628, 2018, A1. Location in patent: Paragraph 00267