New multicomponent cyclization: domino synthesis of pentasubstituted pyridines under solvent-free conditions.

An efficient methodology for the synthesis of highly functionalized pyridine derivatives starting from readily available common reactants has been developed under microwave irradiation and solvent-free conditions. The new domino reaction enables successful assembly of five new σ bonds including two C-N bonds in a one-pot operation. A new mechanism has been proposed, which involves a novel reaction and sequence consisting of deprotonation-imine formation-anionic carbonyl addition.