 A route depicted below lays through first alkylating the same (3-methoxyphenyl)acetonitrile with 2-chloro-"N","N"-dimethylethylamine or 2-chloro-"N"-benzyl-"N"-methylethylamine.Next, those amines are alkylated once again using a mixed 1-bromo-2-chloroethane, thus completing the piperidine ring and obtaining a quaternary ammonium salt, which can be dequaternized using thiophenol salt (for "N","N"-dimethylammonium) or catalytic hydrogenation (for both compounds) to a common 4-(3-methoxyphenyl)-4-cyano-1-methyl-pyperidine.The later yields ketobemidone after Grignard reaction with ethylmagnesium bromide and ether cleavage.