Triphosgene → 6-Bromo-8-chloro-1,2,4-triazolo[4,3-a]pyrazin-3(2H)-one

HRID 2233036Notes

Reaction equation

HRID 2233036 reaction equation
[Br:1][C:2]1[N:3]=[C:4]([Cl:10])[C:5]([NH:8][NH2:9])=[N:6][CH:7]=1.Cl[C:12](Cl)([O:14]C(=O)OC(Cl)(Cl)Cl)Cl>C1COCC1>[Br:1][C:2]1[N:3]=[C:4]([Cl:10])[C:5]2[N:6]([C:12](=[O:14])[NH:9][N:8]=2)[CH:7]=1

Participants

4

Reactant 2

HCID 94429TriphosgeneHCID 584469775-Bromo-3-chloro-2-hydrazinylpyrazine

Product 1

HCID 686778246-Bromo-8-chloro-1,2,4-triazolo[4,3-a]pyrazin-3(2H)-one

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent

Procedure

A solution of 2.50 g of the product of Step C in THF (60 mL) was stirred as 3.32 g of triphosgene was added in portions to provide a tan suspension. A homogeneous solution was obtained after 30 min. and the excess phosgene was destroyed by the careful addition of water and the mixture was extracted with EtOAc. The organic extracts were washed with sat. sodium chloride solution, dried over magnesium sulfate, filtered, and concentrated to afford 6-bromo-8-chloro-2H-[1,2,4]triazolo[4,3-a]pyrazin-3-one as a light yellow solid. MS (M+H−)=280.1.

Workup

  1. additionwas added in portions
  2. customto provide a tan suspension
  3. customA homogeneous solution was obtained after 30 min.
  4. customthe excess phosgene was destroyed by the careful addition of water
  5. extractionthe mixture was extracted with EtOAc
  6. washThe organic extracts were washed with sat. sodium chloride solution
  7. dry with materialdried over magnesium sulfate
  8. filtrationfiltered
  9. concentrationconcentrated

Sources & evidence

ORD record
ord-c175db0b09d6457dafe7d4d421eafc88
Source dataset
uspto-grants-2010_05
Patent number
US07709473B2

Reaction notes

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