Imidazole as organocatalyst for multicomponent reactions: diversity oriented synthesis of functionalized hetero- and carbocycles using in situ-generated benzylidenemalononitrile derivatives

Abstract

The multicomponent reaction of malononitrile, aldehyde and a third reaction partner such as naphthol/4-hydroxycoumarine/2-hydroxynaphthoquinone/kojic acid/enolizable ketone or thiol in the presence of imidazole as an organocatalyst provides very interesting molecular diversity. In an almost neutral reaction medium, this protocol provides easy access to highly functionalized 2-amino-4H-chromenes, dienes and 2-amino pyridines using in situ-generated aryl/alkylylidenemalononitrile derivatives obtained from the reaction of aldehydes and malononitrile along with various nucleophiles under reflux conditions in ethanol. This methodology is useful for the easy access of a wide range of structurally diverse functionalized molecules having potential application in biological systems.