4-Methyl-1,2,3-thiadiazole-5-carbohydrazide → 7-[(2,4-Dichloro-3-fluorophenyl)carbonyl]-3-(4-methyl-1,2,3-thiadiazol-5-yl)-5,6,7,8-tetrahydro[1,2,4]triazolo[4,3-a]pyrazine

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Reaction Steps

Triethyloxonium tetrafluoroborate (330 mg, 1.738 mmol) was added to a suspension of 4-[(2,4-dichloro-3-fluorophenyl)carbonyl]-2-piperazinone (I37) (460 mg, 1.580 mmol) in dry Dichloromethane (DCM) (3.9 ml). The reaction mixture was stirred at room temperature 45 mins—mixture became clear. 4-Methyl-1,2,3-thiadiazole-5-carbohydrazide (300 mg, 1.896 mmol, commercially available) was added and the resulting reaction mixture was stirred at room temperature 2 h 10 min. The solvent was evaporated under reduced pressure. The residue was dissolved in 1-butanol (3.90 ml) and the reaction mixture was stirred at reflux for 17 h. The reaction mixture was diluted in ethyl acetate (150 mL) and washed with water (2×25 mL), sat. NaHCO3 (25 mL) and brine (2×25 mL). The resulting organic layer was dried over MgSO4 and concentrated under reduced pressure. The crude product was purified by MDAP (basic method). The resulting residue was triturated with ether (5×2 mL) and then dried under vacuum at 50° C. to afford the desired product in 117.4 mg as a cream powder.

Provenance & Evidence