CuFe2O4@SO3H: A Mild, Efficient and Reusable Heterogeneous Catalyst for the Synthesis of Highly Functionalized Piperidines

چکیده مقاله

Multi-component reactions (MCRs) are special types of synthetically useful organic reactions in which three or more different starting materials react to give a final product in a one-pot procedure. MCRs are becoming powerful tools in the modern synthesis chemistry due to their efficiency, atom economy, and convenience in the construction of multiple new bonds in onepot processes, which played powerful roles in approaching complex structures and promoting the ‘green chemistry’ [1, 2]. The piperidines and its analogues are important heterocycles that are present in many naturally occurring alkaloids, biologically active synthetic molecules and organic fine chemicals. Some of them also act as pharmaceutical agents. Compounds containing piperidine structural motif exhibit anti-hypertensive, antibacterial, antimalarial, anticonvulsant and anti-inflammatory activities. Thus, the synthesis of highly substituted piperidines has gained considerable attention, and number of procedures have been developed using several approaches such as tandem cyclopropane ring-opening/Conia-ene cyclization, imino Diels-Alder reactions, aza-Prins-cyclizations, intramolecular Michael reactions and intramolecular Mannich reaction onto iminium ions. The functionalized piperidines have been reported using MCRs strategy by employing bromodimethylsulfonium bromide (BDMS), InCl3 and LProline/TFA. However, use of expensive and excess amount of catalysts are some of the disadvantages of the above mentioned methods. Therefore, there is a need for highly efficient, versatile and eco-friendly synthetic protocol to obtain these valuable compounds in good yields [3]. We report herein full details of a novel, convenient, and simple procedure to realize a one-pot pseudo five-component reaction of aldehydes, amines, and 1,3-dicarbonyl compounds, catalyzed by CuFe2O4@SO3H, for the preparation of piperidinecompounds in EtOH with high yields (72-95%) and short times.