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

HRID 421180Notes

Reaction equation

HRID 421180 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>ClCCl>[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 99.3%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Procedure

To a solution of 1.5 g of 1,1-dimethylethyl hexahydro-5H-isothiazolo[2,3-a]pyrazine-5-carboxylate 1,1-dioxide (D9) in 20 ml of dry dichloromethane, under N2 at 0° C., 5 ml of TFA were added drop wise and left to react at 0° C. for 1 h. Then reaction mixture was evaporated under vacuum and crude solid material purified by 50 g SCX cartridge, loading with DCM/MeOH, washing with DCM/MeOH then only with MeOH; product was recovered eluting with 1M NH3 in MeOH. Solvent evaporation gave 0.95 g of pure title compound as white solid.

Workup

  1. waitleft
  2. customto react at 0° C. for 1 h
  3. customThen reaction mixture
  4. customwas evaporated under vacuum
  5. customcrude solid material purified by 50 g SCX cartridge
  6. washwashing with DCM/MeOH
  7. customproduct was recovered
  8. washeluting with 1M NH3 in MeOH
  9. customSolvent evaporation

Sources & evidence

ORD record
ord-92bf95cf76ae4dd2a962f3ca9fbbee91
Source dataset
uspto-grants-2012_01
Patent number
US08097618B2

Reaction notes

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