Solvent-free silica-promoted multicomponent condensation: synthesis of highly functionalized piperidines

摘要

Silica gel has been found to be an efficient and reusable medium for the synthesis of diastereospecific functionalized piperidines in good to high yields by a one-pot three-component condensation of aldehyde, amine and beta-ketoester under solvent-free conditions at room temperature. Using this environmentally benign, non-inflammable and non-toxic reaction medium, the non-chromatographic purification, reusability of the silica gel, and operational simplicity are the notable advantages of the present method. The procedure is applicable for large-scale synthesis of piperidines derivatives and represents a green synthetic protocol.