Synthesis and structure of Schiff bases derived from 3-formyl-4-hydroxycoumarin and diamines

Azomethines containing a π-conjugated imino group (C=N) and benzene ring in the main chain can potentially find broad use as ligands in catalysts, intermediates for thermostable materials, and complexones for metal ions [1-5]. Azomethines of the heterocyclic series are of particular interest. In particular, the 3-acyl4-hydroxycoumarin imines represent remarkable examples of β,β′-tricarbonyl compound derivatives. For instance, compounds 1-3 have an increased tendency to undergo various isomeric transformations [6-9].