Cl[CH2:2][CH2:3][CH2:4][O:5][C:6]1[CH:15]=[CH:14][C:9]([C:10]([O:12][CH3:13])=[O:11])=[CH:8][CH:7]=1.C(=O)([O-])[O-].[K+].[K+].[CH3:22][C@H:23]1[CH2:28][C@H:27]([CH3:29])[CH2:26][NH:25][CH2:24]1.[I-].[K+]>CN(C)C=O>[CH3:13][O:12][C:10]([C:9]1[CH:14]=[CH:15][C:6]([O:5][CH2:4][CH2:3][CH2:2][N:25]2[CH2:26][C@@H:27]([CH3:29])[CH2:28][C@H:23]([CH3:22])[CH2:24]2)=[CH:7][CH:8]=1)=[O:11]A mixture of methyl 4-(3-chloropropoxy)benzoate (4.57 g), potassium carbonate (8.29 g), cis and trans-3,5-dimethylpiperidine (5.31 mL) and a catalytic amount of potassium iodide in N,N-dimethylformamide (100 mL) is stirred overnight at 100° C. The suspension is filtrated and the precipitate washed with ethanol. The filtrate is concentrated under reduced pressure and purified by chromatography over silica gel with a gradient of dichloromethane/methanol from 98/2 to 90/10. Fraction containing the expected products are pooled and concentrated under reduced pressure yielding 5.33 g of cis and trans-1-{3-[4-(methoxycarbonyl)phenoxy]propyl}-3,5-dimethylpiperidine.
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