Cyclization of O-benzoyl-β-piperidinopropionamidoximes to form 5-phenyl-3-(β-piperidino)ethyl-1,2,4-oxadiazoles

The reactions of -piperidinopropionamidoxime with substituted benzoyl chlorides afforded O-benzoylation products, which underwent cyclization to form 5-phenyl-3-(-piperidino)ethyl-1,2,4-oxadiazoles upon heating in dimethylformamide in the presence of molecular sieves at 60 °C for 1—2.5 h. Heating of O-benzoyl--piperidinopropionamidoxime in dimethylformamide in the presence of K₂CO₃ at 85 °C for 4 h afforded a mixture of 5-phenyl-3-(-piperidino)ethyl-1,2,4-oxadiazole, benzoic acid, and N-(-piperidino)ethylurea.