Formaldehyde → Ethyl 1-(4-fluorophenyl)-4-hydroxy-1,3,8-triazaspiro[4.5]dec-3-ene-8-carboxylate

Participants

Reaction Steps

To a solution of 6.9 parts of paraformaldehyde in 100 parts of N,N-dimethylformamide are added portionwise 46.3 parts of ethyl 4-carbamoyl-4-(4-fluorophenylamino)-1-piperidinecarboxylate. The whole is stirred and refluxed for 20 hours. Then 50 parts of the solvent are distilled off (t°: 142°-152° C.). A second portion of 1 part of paraformaldehyde in 50 parts of N,N-dimethylformamide is added and stirring and refluxing is continued for 48 hours. The N,N-dimethylformamide is distilled off to a volume of about 50 parts and the distillate is poured onto water. The water is decanted and the residue is extracted with trichloromethane. The extract is washed with water, dried, filtered and evaporated. The residue is triturated in 2,2'-oxybispropane. The product is filtered off and crystallized from a mixture of benzene and 2,2'-oxybispropane, yielding 17.5 parts of ethyl 1-(4-fluorophenyl)-4-oxo-1,3,8-triazaspiro[4,5]decane-8-carboxylate; mp. 153° C.

Provenance & Evidence