Pyrazine-2-Carboxylic Acid Hydrazide → 7-[(2,4-Dichlorophenyl)carbonyl]-3-(2-pyrazinyl)-5,6,7,8-tetrahydro[1,2,4]triazolo[4,3-a]pyrazine

HRID 1889078Notes

Reaction equation

HRID 1889078 reaction equation
[Cl:1][C:2]1[CH:7]=[C:6]([Cl:8])[CH:5]=[CH:4][C:3]=1[C:9]([N:11]1[CH2:16][CH2:15][NH:14][C:13](=O)[CH2:12]1)=[O:10].F[B-](F)(F)F.C([O+](CC)CC)C.[N:30]1[CH:35]=[CH:34][N:33]=[CH:32][C:31]=1[C:36]([NH:38][NH2:39])=O>ClCCl>[Cl:1][C:2]1[CH:7]=[C:6]([Cl:8])[CH:5]=[CH:4][C:3]=1[C:9]([N:11]1[CH2:16][CH2:15][N:14]2[C:36]([C:31]3[CH:32]=[N:33][CH:34]=[CH:35][N:30]=3)=[N:38][N:39]=[C:13]2[CH2:12]1)=[O:10]

Participants

5

Reactant 3

HCID 258796Pyrazine-2-Carboxylic Acid HydrazideHCID 2723982Triethyloxonium tetrafluoroborateHCID 302889354-(2,4-Dichlorobenzoyl)piperazin-2-one

Product 1

HCID 665988177-[(2,4-Dichlorophenyl)carbonyl]-3-(2-pyrazinyl)-5,6,7,8-tetrahydro[1,2,4]triazolo[4,3-a]pyrazine

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Procedure

A solution of 4-[(2,4-dichlorophenyl)carbonyl]-2-piperazinone (I6) (0.273 g, 1 mmol) in dry Dichloromethane (DCM) (3 ml) was stirred at room temperature under argon. Triethyloxonium tetrafluoroborate (0.199 g, 1.050 mmol) was added and the reaction solution was stirred for 10 minutes. 2-pyrazinecarbohydrazide (0.166 g, 1.200 mmol, commercially available) was then added and the solution was stirred for a further 1 hour. The solvent was then concentrated before n-butanol (3.00 ml) was added and the solution was stirred, under reflux and argon, for 4 hours. LCMS confirmed product location, thus the solution was cooled to room temperature before the solvent was evaporated in vacuo. The remaining residue was then purified by flash chromatograpghy (Biotage SP4, 25M cartridge) with a gradient of 0 to 10% 2M NH3/MeOH in DCM. TLC confirmed product location and the solvent from the combined fractions was evaporated in vacuo. The remaining residue was then further purified by mass-directed automated HPLC. The solvent was then evaporated in vacuo, and the remaining solid was triturated with ether, and dried in a vacuum oven to yield the product in 0.137 g.

Workup

  1. stirringthe solution was stirred for a further 1 hour
  2. concentrationThe solvent was then concentrated before n-butanol (3.00 ml)
  3. additionwas added
  4. stirringthe solution was stirred
  5. temperatureunder reflux
  6. waitargon, for 4 hours
  7. customwas evaporated in vacuo
  8. customThe remaining residue was then purified by flash chromatograpghy (Biotage SP4, 25M cartridge) with a gradient of 0 to 10% 2M NH3/MeOH in DCM
  9. customthe solvent from the combined fractions was evaporated in vacuo
  10. customThe remaining residue was then further purified
  11. customThe solvent was then evaporated in vacuo
  12. customthe remaining solid was triturated with ether
  13. customdried in a vacuum oven
  14. customto yield the product in 0.137 g

Sources & evidence

ORD record
ord-25c4e5021d5a4953916ab1a7ec753df5
Source dataset
uspto-grants-2013_08
Patent number
US08501946B2

Reaction notes

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