Sodium Carbonate → methyl 4-[N-(4-chlorophenyl)acetyl-N-phenylamino]-1-(1-methylethyl)-4-piperidinecarboxylate ethanedioate

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Reaction Steps

a mixture of 5 parts of methyl 1-(1-methylethyl)-4-(phenylamino)-4-piperidinecarboxylate, 24 parts of 4-chlorobenzeneacetyl chloride, 4 parts of sodium carbonate and 180 parts of dimethylbenzene is stirred and refluxed for 32 hours. The reaction mixture is cooled, washed with a diluted sodium hydroxide solution and extracted with a diluted hydrochloric acid solution: three layers are obtained. The oil and the aqueous phase are combined and alkalized with a diluted sodium hydroxide solution. The product is extracted with 4-methyl-2-pentanone. The extract is washed with water, dried, filtered and evaporated. The residue is converted into the ethanedioate salt in 2-propanol. The salt is filtered off and crystallized from a mixture of 2-propanol and 2,2'-oxybispropane, yielding 5 parts (48%) of methyl 4-[N-(4-chlorophenyl)acetyl-N-phenylamino]-1-(1-methylethyl)-4-piperidinecarboxylate ethanedioate; mp. 154.2° C.

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