C([N:8]1[CH2:13][CH2:12][N:11]([C:14]([O:16][C:17]([CH3:20])([CH3:19])[CH3:18])=[O:15])[CH2:10][CH:9]1[CH:21]([F:23])[F:22])C1C=CC=CC=1.[H][H]>[Pd].CO.[OH-].[OH-].[Pd+2]>[F:23][CH:21]([F:22])[CH:9]1[NH:8][CH2:13][CH2:12][N:11]([C:14]([O:16][C:17]([CH3:19])([CH3:18])[CH3:20])=[O:15])[CH2:10]110% Palladium on carbon (65 mg, 0.061 mmol) was added to a solution of tert-butyl 4-benzyl-3-(difluoromethyl)piperazine-1-carboxylate (0.20 g, 0.61 mmol, racemic from Step 3) in methanol (15 mL). The suspension was stirred under an atmosphere of hydrogen provided by a balloon. When the reaction showed no progress, 20% Pd(OH)2 on charcoal (47 mg, 0.061 mmol) was added and the suspension was shaken under 50-55 psi hydrogen for 2 h. The mixture was filtered and solvent removed in vacuo to afford product as a viscous oil (140 mg, 97%). 1H NMR (300 MHz, CDCl3): δ 5.90 (td, 0.1H), 5.52-5.12 (br s, 2H), 4.25-3.96 (br s, 1H), 3.94 (d, 1H), 3.27-2.77 (m, 4H), 1.45 (s, 9H); LCMS (M-tBu+2H)+: 181.0.
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