Triethyloxonium tetrafluoroborate → 2-{7-[(2,4-Dichloro-3-fluorophenyl)carbonyl]-5,6,7,8-tetrahydro[1,2,4]triazolo[4,3-a]pyrazin-3-yl}-3-pyridinol

Beteiligte Stoffe

Reaktionsschritte

Triethyloxonium tetrafluoroborate (341 mg, 1.795 mmol) was added under argon to a solution of 4-[(2,4-dichloro-3-fluorophenyl)carbonyl]-2-piperazinone (I37) (475 mg, 1.632 mmol) in dry Dichloromethane (DCM) (4 mL). The mixture was stirred at room temperature for 1 hour 15 min—the solution was clear. 3-hydroxy-2-pyridinecarbohydrazide (I93) (300 mg, 1.958 mmol) was added under argon. The reaction was stirred at room temperature overnight. The solvent was evaporated under reduced pressure and the remaining residue was dissolved in 1-butanol (4.00 mL). The mixture was stirred at reflux 1 day. The solvent was evaporated under reduced pressure. The remaining residue was dissolved into ethyl acetate (75 mL), extracted with water (3×10 mL) and with brine (2×10 mL). The organic layer was dried over MgSO4 and concentrated under reduced pressure. The crude product was purified by MDAP. The resulting solid was triturated in diethyl ether (15 mL) and dried under vacuum at 50° C. for 3 days to afford the desired product in 9.0 mg as a pinkish powder.

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