[CH3:1][CH:2]1[CH2:7][C:6](=[O:8])[CH:5]=[CH:4][N:3]1[C:9]([O:11][CH2:12][C:13]1[CH:18]=CC=C[CH:14]=1)=[O:10].C(OC(OC(OC(C)(C)C)=O)=O)(C)(C)C.[H][H]>[Pd].C(OCC)(=O)C>[CH3:14][CH:13]([CH3:18])[CH2:12][O:11][C:9]([N:3]1[CH2:4][CH2:5][C:6](=[O:8])[CH2:7][CH:2]1[CH3:1])=[O:10]
A mixture of 1.1 g of the crude 2(R,S)-methyl-1(benzyloxycarbonyl)-2,3-dihydro-4-pyridone, 200 mL of ethyl acetate, 1 g of di-tert-butyldicarbonate and 1 g of 10% palladium on carbon was shaken under 55 psi of hydrogen for 24 h. The mixture was filtered, concentrated under reduced pressure, and purified by low pressure chromatography on silica gel eluting with 40% ethyl acetate in hexane. There was obtained first 0.20 g of (±)-1-(2,2-dimethylethoxycarbonyl)-2-methyl-4-oxopiperidine: 1H NMR (400 MHz, CDCl3) 4.65 (m, 1H), 4.2 (m, 1H), 3.3 (m, 1H), 2.65 (dd, 1H), 2.45 (m, 1H), 2.3 (m, 1H), 2.2 (dd, 1H), 1.45 (s, 9H), 1.14 (d, 3H). Later fractions gave 0.50 g of the (±)-1-(2,2-dimethylethoxycarbonyl)-2-methyl-4-hydroxypiperidine: 1H NMR (400 MHz, CDCl3) 4.3 (m, 1H), 4.15 (t, 1H), 3.8 (m, 1H), 3.25 (m, 1H), 2.15 (s, 1H), 2.8 (m, 1H), 1.65 (m, 3H), 1.42 (s, 3H), 1.25 (d, 3H).
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