p-Toluenesulfonic acid → [(1R,2S)-1-carboxy-2-hydroxy-propyl]-methyl-ammonium toluene-4-sulfonate
Reaction equation
C(O[C:6]([N:8](C)[C@H:9]([C@@H:13]([OH:15])[CH3:14])[C:10]([OH:12])=[O:11])=O)(C)(C)C.[CH3:17][C:18]1[CH:19]=[CH:20][C:21]([S:24]([OH:27])(=[O:26])=[O:25])=[CH:22][CH:23]=1.C(O)(C(F)(F)F)=O>>[C:18]1([CH3:17])[CH:19]=[CH:20][C:21]([S:24]([O-:27])(=[O:25])=[O:26])=[CH:22][CH:23]=1.[C:10]([C@H:9]([NH2+:8][CH3:6])[C@@H:13]([OH:15])[CH3:14])([OH:12])=[O:11]Participants
Conditions
- Temperature
- 0 °C
Procedure
In a heart-shaped flask, (2R,3S)-2-[tert-butoxycarbonyl-(methyl)-amino]-3-hydroxy-butanoic acid (0.086 g, 0.37 mmol) was mixed with p-TsOH (0.073, 0.39 mmol) and the solid mixture was cooled to 0° C. Subsequently TFA (2.0 mL) was added over 10 min and the reaction mixture was left to react for 15 min at 0° C. The solution was rotary evaporated maintaining the bath below 30° C. and the obtained oil was left under vacuum for 1 h. The oil was then dissolved in dry Et2O to form a white precipitate. The solution was decanted and the solid washed several times with the same solvent to give a pure product (0.11 g, quant.), as a white sticky solid. 1H NMR (DMSO-d6) δ 1.25 (d, J=6.5 Hz, 3H), 2.29 (s, 3H), 2.60 (s, 3H), 3.73-3.82 (m, 1H), 4.02-4.11 (m, 1H), 7.11 (d, J=8.1 Hz, 2H), 7.48 (d, J=8.1 Hz, 2H).
Workup
- waitthe reaction mixture was left
- customto react for 15 min at 0° C
- customThe solution was rotary evaporated
- temperaturemaintaining the bath below 30° C.
- dissolutionThe oil was then dissolved in dry Et2O
- customto form a white precipitate
- customThe solution was decanted
- washthe solid washed several times with the same solvent
- customto give a pure product (0.11 g, quant.)
Sources & evidence
- ORD record
- ord-4386b2c43d9d445eb6db3b65d4c1e962
- Source dataset
- uspto-grants-2016_05
- Patent number
- US09353075B2
Reaction notes
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