Trifluoroacetic acid → Hexahydro-2H-isothiazolo[2,3-a]pyrazine 1,1-dioxide

HRID 921949Notes

Reaction equation

HRID 921949 reaction equation
[S:1]1(=[O:18])(=[O:17])[N:5]2[CH2:6][CH2:7][N:8](C(OC(C)(C)C)=O)[CH2:9][CH:4]2[CH2:3][CH2:2]1.C(O)(C(F)(F)F)=O>C(Cl)Cl>[S:1]1(=[O:17])(=[O:18])[N:5]2[CH2:6][CH2:7][NH:8][CH2:9][CH:4]2[CH2:3][CH2:2]1

Participants

4

Reactant 2

HCID 6422Trifluoroacetic acidHCID 59215825tert-butyl 1,1-dioxo-hexahydro-2H-1lambda6-[1,2]thiazolo[2,3-a]piperazine-5-carboxylate

Product 1

HCID 59215775Hexahydro-2H-isothiazolo[2,3-a]pyrazine 1,1-dioxideYield 83.9%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Procedure

tert-butyl tetrahydro-2H-isothiazolo[2,3-a]pyrazine-5(3H)-carboxylate 1,1-dioxide (200 mg, 0.724 mmol) in DCM (3 mL) was treated with TFA (1.059 mL, 13.75 mmol) at room temperature for 1 h. Solvent was evaporated and the residue was redissolved in DCM and concentrated again. The crude was purified by SCX cartridge, loading with MeOH, washed with additional MeOH. Product was recovered eluting with 2M NH3 in MeOH. Solvent evaporation give hexahydro-2H-isothiazolo[2,3-a]pyrazine 1,1-dioxide (107 mg)

Workup

  1. customSolvent was evaporated
  2. dissolutionthe residue was redissolved in DCM
  3. concentrationconcentrated again
  4. customThe crude was purified by SCX cartridge
  5. washwashed with additional MeOH
  6. customProduct was recovered
  7. washeluting with 2M NH3 in MeOH
  8. customSolvent evaporation

Sources & evidence

ORD record
ord-8bea9b8cb3cf4972a205cf614bc493b5
Source dataset
uspto-grants-2016_03
Patent number
US09273057B2

Reaction notes

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