Multicomponent Reactions for Diverse Synthesis of N-Substituted and NH 1,4-Dihydropyridines

The multicomponent reactions of aldehydes, electron deficient alkynes and amines have been successfully performed to yield a number of symmetrical 2,6-unsubstituted 1,4-dihydropyridines (1,4-DHPs). This method has been found generally applicable for the synthesis of both N-substituted and N-unsubstituted 1,4-DHPs by employing secondary amine to activate the alkyne component via enaminoester intermediates. The present method runs through an enamine type activation, which is different from the known approach employing AcOH as solvent.