Improved methodologies for the preparation of highly substituted pyridines

The two complementary procedures for the 'one-pot' synthesis of highly substituted pyridines, one using microwave irradiation as the key technological advance and the second approach based on tethered imine-enamine (TIE) methodology is described. Both routes do not need discrete aromatization step and offer significant advantages over the classical methods giving a wide variety of tri-, tetra-, and penta-substituted pyridines in high optimized yields.