Triethyloxonium tetrafluoroborate → 7-[(2,3-Dichloro-4-fluorophenyl)carbonyl]-3-(5-fluoro-2-pyridinyl)-5,6,7,8-tetrahydro[1,2,4]triazolo[4,3-a]pyrazine

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Reaction Steps

To a solution of 4-[(2,3-dichloro-4-fluorophenyl)carbonyl]-2-piperazinone (I34) (5.08 g, 17.45 mmol) in Dichloromethane (DCM) (80 mL) was added triethyloxonium tetrafluoroborate (3.48 g, 18.32 mmol). The solution was then stirred under argon for 20 minutes before 5-fluoro-2-pyridinecarbohydrazide (I24) (3.25 g, 20.94 mmol) was added. The solution was then stirred for a further 3 hours, before the solvent was concentrated and n-butanol (80 mL) was added. The solution was then stirred, under reflux and argon, for 3 hours before being cooled to room temperature. The solvent was then evaporated in vacuo and the remaining residue was partioned between DCM (100 mL) and water (50 mL), before being dried over anhydrous sodium suphate. The sodium sulphate was then removed by filtration, and the solvent was evaporated in vacuo. The remaining residue was then purified by flash chromatography (Isolera 340 g cartridge) with a gradient of 0-10% MeOH in DCM, TLC confirmed product location and the solvent from the combined fractions was evaporated in vacuo. The remaining solid was then recrystallised from ethyl acetate to yield the product in 2.067 g.

Provenance & Evidence