[C:1]1([CH2:7][O:8][CH:9]2[C:14](=[O:15])[CH2:13][CH2:12][N:11](CC3C=CC=CC=3)[CH2:10]2)[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.ClCCl.[C:26](Cl)(=[O:30])[O:27][CH2:28][CH3:29]>C(N(CC)CC)C>[O:15]=[C:14]1[CH2:13][CH2:12][N:11]([C:26]([O:27][CH2:28][CH3:29])=[O:30])[CH2:10][CH:9]1[O:8][CH2:7][C:1]1[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1To a stirred mixture of 10 parts of 3-(phenylmethoxy)-1-(phenylmethyl)-4-piperidinone and 65 parts of dichloromethane were added dropwise 5 parts of ethyl carbonochloridate at room temperature. After stirring for 6.30 hours at reflux, there were added 5 parts of N,N-diethylethanamine. Upon completion, stirring at reflux was continued for 24 hours. The reaction mixture was washed successively with water, a diluted hydrochloric acid solution and again with water, dried, filtered and evaporated. The residue was purified by column-chromatography over silica gel using a mixture of trichloromethane and methanol (95:5 by volume) as eluent. The pure fractions were collected and the eluent was evaporated, yielding 8.1 parts (86.5%) of ethyl 4-oxo-3-(phenylmethoxy)-1-piperidinecarboxylate as an oily residue (intermediate 47).
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