Trisodium citrate dihydrate catalyzed one-pot pseudo four-component synthesis of fully functionalized pyridine derivatives

A facile and convenient method has been developed for the one-pot pseudo-four component synthesis of fully functionalized pyridine derivatives from the reactions of aromatic aldehydes, malononitrile and thiols in the presence of a catalytic amount of trisodium citrate dihydrate as an efficient metal-free catalyst in aqueous ethanol under refluxed conditions. All the reactions were completed within just 45 minutes and the desired products afforded in excellent yields (90-95%). Gram scale production of the desired compound was also achieved. Synthesis of biologically promising scaffolds, high atom economy, excellent yields, use of metal-free catalyst, less toxic solvents, no column chromatographic purifications, reusability of the solvent media, multiple carbon-carbon and carbon-heteroatom bond formations are some of the major advantages of this newly developed protocol.