87597-21-5

70-23-5

24241-18-7

87597-21-5

Step A: Preparation of ethyl 6,8-dibromoimidazo[1,2-a]pyrazine-2-carboxylate At room temperature, 2-amino-3,5-dibromopyrazine (20 g, 79 mmol) was dissolved in dimethyl carbonate (133 mL) and stirred until completely dissolved. Subsequently, ethyl 3-bromo-2-oxopropionate (17.14 g, 79 mmol) was added to the reaction system in one go. The reaction mixture was heated to 110 °C with continuous stirring for 3 hours. Upon completion of the reaction, the mixture was cooled to room temperature and stirring was continued overnight. Water and dichloromethane (DCM) were added to the reaction mixture, the aqueous phase was separated and extracted with DCM. The organic phases were combined, washed with water, dried over anhydrous sodium sulfate (Na2SO4), filtered and the solvent evaporated. Purification by fast column chromatography afforded 13.95 g (50.6% yield) of ethyl 6,8-dibromoimidazo[1,2-a]pyrazine-2-carboxylate, the target compound. The product was characterized by 1H-NMR (300 MHz, CDCl3): δ= 8.30 (s, 1H), 8.27 (s, 1H), 4.48 (q, 2H), 1.43 (t, 3H) ppm.