One pot synthesis of pyrazole 4-carboxylic acid ethyl ester derivatives by magnetic ionic liquid and flow oxygen

Imidazolium-based ionic liquids, containing perrhenate anions, are very efficient reaction media for the one-pot synthesis of pyrazole 4-carboxylic acid ethyl ester derivatives with flow oxygen as an oxidant. Th e proposed protocol via three-component reaction involving phenylhydrazine, benzaldehyde and ethyl acetoacetate the presence of [bmim][FeCl4] has some advantages such as application of environmentally friendly and recyclable catalyst, green process, good to excellent yield, mild reaction condition, ease of operation and work-up.