1-Benzyl-4-methyl-4-phenylpiperidine → 4-Methyl-4-phenylpiperidine

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Reaction Steps

Freshly prepared methanolic formic acid solution (4.4% by weight, 70 mL) was added to 1-benzyl-4-methyl-4-phenylpiperidine (3.23 g, 12.2 mmol). To the resulting solution was added 10% palladium on carbon (2.00 g). The mixture was stirred at room temperature for 24 hours. The solid was filtered out and washed with MeOH (30 mL), H2O (15 mL), CH2Cl2 (30 mL) and MeOH (15 mL). The combined filtrate and washings were concentrated, and the residue was dissolved in CH2Cl2 (50 mL) and H2O (10 mL). The aqueous phase was adjusted to pH 11 by addition of 1 N aqueous NaOH. The organic phase was separated, dried over magnesium sulfate and concentrated. The residual oil was purified by flash chromatography (CHCl3/MeOH/2 N NH3 in MeOH 100/4/0 to 100/20/10), giving 1-benzyl-4-methyl-4-phenylpiperidine (1.20 g) and 1.10 g (51%, 82% based on consumed starting material) of 4-methyl-4-phenylpiperidine: 1H NMRδ 1.24 (s, 3 H), 1.71 (m, 2 H), 2.06 (m, 2 H), 2.82 (m, 3 H), 2.94 (m, 2 H), 7.19 (m, 1 H), 7.32 (m, 4 H); 13C NMR δ 37.22, 38.54, 43.44, 47.74, 126.31, 127.43, 129.01, 149.73.

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