Lewis acid-catalyzed reaction between tertiary enamides and imines of salicylaldehydes: expedient synthesis of novel 4-chromanamine derivatives

In the presence of a catalytic amount of Zn(OTf)(2) in DCE at ambient temperature, a number of tertiary enamides underwent highly efficient reaction with imines of salicylaldehydes to afford diverse functionalized 4-chromanamine derivatives in high yields. The reaction proceeds most probably through an enaminic addition of tertiary enamides to imine functionality followed by the intramolecular interception of the resulting iminium intermediate by the phenolic hydroxy group. The synthesis was also practically implemented by means of a three-component reaction starting from salicylaldehyde, para-nitroaniline, and a tertiary enamide. (C) 2014 Published by Elsevier Ltd.