1-Benzyl 4-methyl 4-allylpiperidine-1,4-dicarboxylate → 1-Benzyl 4-methyl 4-(2-oxoethyl)piperidine-1,4-dicarboxylate

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Reaction Steps

To a solution of 1-benzyl 4-methyl 4-allylpiperidine-1,4-dicarboxylate from Step B (4.45 g, 14.0 mmol) in THF (70 mL) at 0° C. was added borane-methyl sulfide complex (28.0 mL of a 2M solution in THF, 56.1 mmol). The reaction mixture was slowly warmed to ambient temperature and stirred for 16 h, then quenched with water and concentrated in vacuo. The residue was dissolved in CH2Cl2 (140 mL) and added drop wise to a solution of PCC (6.65 g. 30.8 mmol) and 4 Å molecular sieves (6.65 g) in CH2Cl2 (50 mL) at 0° C. The reaction mixture was warmed to ambient temperature and stirred for 16 h, then diluted with ether (200 mL) and filtered through a pad of celite. Additional ether was used to wash the celite. The combined organics were concentrated in vacuo to give a residue that was purified by silica gel chromatography, eluting with a gradient of CH2Cl2:MeOH—100:0 to 95:5, to give the title compound. MS: m/z=356 (M+Na).

Provenance & Evidence