8-CHLORO-2-METHYLIMIDAZO[1,2-A]PYRAZINE

Synthesis

The reaction was carried out with 2-amino-3-chloropyrazine (48.7 g, 375.8 mmol) and chloroacetone (120 mL, 1504.5 mmol) in a sealed tube with stirring for 16 h at 90 °C under light protection. Upon completion of the reaction, it was cooled to room temperature, ether (Et2O) was added and the solid product formed was collected by filtration. After washing the solid with additional ether, it was suspended in saturated sodium carbonate solution and extracted with dichloromethane (DCM). The organic layer was separated, dried with anhydrous sodium sulfate (Na2SO4), filtered and concentrated in vacuum to remove the solvent. The crude product was purified by recrystallization from ether to give Intermediate 4 (43.2 g, 68% yield) as a white solid, which could be used in subsequent reactions without further purification. The melting point of the intermediate was 133.5-138.6 °C (determined by WRS-2A melting point apparatus).

References

[1] Patent: WO2011/110545, 2011, A1. Location in patent: Page/Page column 73-74
[2] Patent: US2012/329792, 2012, A1. Location in patent: Page/Page column 33-34
[3] Journal of Medicinal Chemistry, 2014, vol. 57, # 10, p. 4196 - 4212
[4] Patent: US2015/203498, 2015, A1. Location in patent: Paragraph 0167; 0168
[5] Patent: WO2016/185342, 2016, A1. Location in patent: Page/Page column 39