Metal-Free Multicomponent Syntheses of Pyridines

Multicomponent reactions (MCR) are very attractive because of their efficiency and simplicity, appealing for pharmaceutical companies interested in rapidly accessing new medicines. The compilation of the existent literature focuses on the pyridine ring construction and has been organized according to the main reaction involved in each process. It is interesting to note that although they have known significant developments in the past decade, most of them are based on old but well-known reactions. As early as 1980, Kambe and Saito were interested in a synthetic approach to 2-aminopyridines and thought about using malononitrile in the modified Chichibabin synthesis. A single example demonstrated that the reaction could be performed with 2- naphthol derivatives as well.