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.
