New domino heteroannulation of enaminones: synthesis of diverse fused naphthyridines

A series of new poly-functionalized fused naphthyridine derivatives were synthesized via a three-component reaction of aldehyde, 2-aminoprop-1-ene-1,1,3-tricarbonitrile and enaminone in EtOH using EtONa as a base. During these reaction processes, the domino construction of fused naphthyridine skeleton with concomitant formation of two new pyridine rings was readily achieved via base promoted three-component reactions in a one-pot operation. The procedures are facile, avoiding time-consuming and costly syntheses, tedious work-up and purifications of precursors.