3-chloro-7H-pyrrolo[2,3-c]pyridazine

Synthesis

General procedure for the synthesis of 3-chloro-7H-pyrrolo[2,3-c]pyridazine from 6-chloro-4-((trimethylmethylsilyl)ethynyl)pyridazin-3-amine: to a stirring solution of 6-chloro-4-((trimethylmethylsilyl)ethynyl)pyridazin-3-amine (10g, 44.4mmol) in DMF (150mL) was added sequentially t-BuOK ( 7.4 g, 66 mmol) and Me2NH (0.4 g, 8.8 mmol). The reaction mixture was stirred at 120 °C for 2 hours. Upon completion of the reaction, the reaction was quenched by addition of saturated aqueous NaHCO3 solution (50 mL). The reaction mixture was filtered and the filter cake was washed twice with EtOAc (50 mL). The organic phases were combined, washed with brine, dried over anhydrous Na2SO4, filtered and concentrated in vacuum to give the crude product. The crude product was purified by rapid chromatography on silica gel (petroleum ether/EtOAc, 8:1 to 3:1) to afford 3-chloro-7H-pyrrolo[2,3-c]pyridazine (2 g, 30% yield) as a solid.MS (ESI): m/z 154.2 [M + H]+.

References

[1] Patent: WO2017/133667, 2017, A1. Location in patent: Page/Page column 171
[2] Patent: US2011/82138, 2011, A1
[3] Patent: WO2011/143646, 2011, A1. Location in patent: Page/Page column 58
[4] Patent: WO2017/133665, 2017, A1. Location in patent: Page/Page column 51-52