Phosphorus oxychloride → 5-chloro-1-(2,4-difluorophenyl)-7-ethyl-1H-pyrazolo[4,3-b]pyrazin-6(7H)-one

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Reaction Conditions

Reaction Steps

A mixture of 1-(2,4-difluorophenyl)-7-ethyl-1H-pyrazolo[3,4-b]pyrazine-5,6(4H,7H)-dione (330 mg, 1.13 mmol) in 5 mL of toluene was treated with POCl3 (0.16 mL, 1.70 mmol) followed by N,N-diisopropylethylamine (0.16 mL, 0.9 mmol). The reaction mixture was heated in an oil bath at 110° C. for 2.5 h. The volatiles were removed on the rotovap and the residue was dissolved in ice cold DCM (20 mL) and washed with NaHCO3 saturated solution, dried over MgSO4, filtered and concentrated affording 5-chloro-1-(2,4-difluorophenyl)-7-ethyl-1H-pyrazolo[4,3-b]pyrazin-6(7H)-one as a brown amorphous solid. The material was used without further purification. MS (ES+): 311.0 (M+H)+.

Provenance & Evidence