Methanol → 3-p-Methoxybenzyl-2-piperidone

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This example describes the preparation of I where n=2 and R1=p-methoxyphenyl. In a nitrogen-filled glove box, a Fisher-Porter tube was charged with iridium catalyst prepared as in Example 1 (10 mg, 0.012 mmol) and 3-(p-methoxybenzylidene)-2-piperidone (250 mg, 1.2 mmol). Methanol (3 mL) and dichloromethane (3 mL) were added and the system was flushed 4 times with hydrogen and pressured to 60 psi (0.5 MPa) H2. After 18 h the reaction mixture was filtered through a short pad of silica. The solvent was removed at reduced pressure to afford 3-p-methoxybenzyl-2-piperidone (230 mg, 92%) as a white crystalline solid. Chiral HPLC analysis (Chiralpak AS, 60% heptane, 39.2% isopropanol, 0.4% trifluoroacetic acid, 0.4% n-hexylamine, 40° C.) indicated that conversion was 100% and the enantiomeric excess was 83%. 13C NMR: δ 21.32, 25.49, 36.72, 42.56, 43.11, 55.40, 113.93, 130.37, 131.99, 158.18, 174.93; 1H NMR: δ 1.44 (m, 1H), 1.62 (m, 1H), 1.68-1.75 (m, 2H), 2.50 (m, 1H), 2.64 (app. dd, 1H), 3.20-3.37 (m, 3H), 3.79 (s, 3H), 6.82 (d, J=9 Hz, 2H), 7.09 (br s, 1H), 7.12 (d, J=9 Hz, 2H).

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