Trifluoroacetic acid → Hexahydro-2H-isothiazolo[2,3-a]pyrazine 1,1-dioxide
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]1Participants
4
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.