[F:1][C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][C:3]=1[C:8]1([C:24]#N)[CH2:13][CH2:12][N:11](S(C2C=CC(C)=CC=2)(=O)=O)[CH2:10][CH2:9]1.S(=O)(=O)(O)O.[OH-:31].[NH4+].[CH2:33]([OH:35])[CH3:34]>>[F:1][C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][C:3]=1[C:8]1([C:24]([O:35][CH2:33][CH3:34])=[O:31])[CH2:9][CH2:10][NH:11][CH2:12][CH2:13]1A mixture of 35.8 parts of 4-(2-fluorophenyl)-1-(4-methylphenylsulfonyl)-4-piperidinecarbonitrile and 50 parts of a sulfuric acid solution 75% is stirred for 4 hours at about 150° C. 192 Parts of ethanol are added dropwise. Upon completion, stirring is continued for 5 hours at reflux temperature. The reaction mixture is cooled and poured onto crushed ice. The whole is alkalized with ammonium hydroxide and the product is extracted with dichloromethane. The extract is dried, filtered and evaporated, yielding 17.2 parts (68.4%) of ethyl 4-(2-fluorophenyl)-4-piperidinecarboxylate as a residue.
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