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

Abstract

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