[NH2:1][C@@H:2]([CH2:6][C:7]1[CH:12]=[CH:11][C:10]([CH3:13])=[CH:9][CH:8]=1)[C:3]([OH:5])=[O:4].[C:14]([OH:20])([C:16]([F:19])([F:18])[F:17])=[O:15]>O=[Pt]=O.O>[C:14]([OH:20])([C:16]([F:19])([F:18])[F:17])=[O:15].[NH2:1][C@@H:2]([CH2:6][CH:7]1[CH2:8][CH2:9][CH:10]([CH3:13])[CH2:11][CH2:12]1)[C:3]([OH:5])=[O:4]A 250 mL Parr shaker vessel was charged with 1.0 g (5.6 mmol) of (S)-2-amino-3-p-tolylpropanoic acid, 63 mg (0.28 mmol, 5 mol %) of PtO2, and 10 mL of 1:1 TFA:water. The vessel was placed in a Parr hydrogenation shaker, pressurized to 50 psi, and shaken for 2 d. Analysis of the mixture by LC/MS indicated a ca 1:1 mixture of cis:trans isomers. The contents were filtered through a pad of Celite and the spent catalyst washed with additional water. The clear filtrate was evaporated to afford crude TFA salt of (S)-2-amino-3-(4-methylcyclohexyl)propanoic acid which was used directly in the next step.
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