Reaction between alkyl isocyanides and 3-formylchromones in the presence of monocyclic unsaturated acyl compounds: Competition between Friedel-Crafts acylation and Diels-Alder cycloaddition

Abstract

The highly reactive alkylaminofurochromenone intermediate, produced from the reaction between 3-formylchromones and alkyl isocyanides, was trapped by monocyclic unsaturated acyl compounds such as maleic anhydride or maleimide derivatives to yield new types of organic fluorophores 4-(alkylamino)-1H-furo[3,4-b]xanthene-1,3,10-triones or 4-(alkylamino)chromeno[2,3-f]isoindole-1,3,10(2H)-triones, which exhibited strong sky blue emission in solution. The reaction is very simple from an experimental point-of-view and allows the creation of a fused benzene ring with concomitant formation of three new C–C bonds in a single operation.