Triple-Dearomative Photocycloaddition – A Strategy to Construct Novel Caged Molecular Frameworks

Abstract

An unprecedented, caged 2H-benzo-dioxo-pentacycloundecane (BDPC) framework was serendipitously obtained in a single transformation via a triple-dearomative photocycloaddition of chromone esters with furans. This caged structure was generated during the course of an effort to access a tricyclic, oxygen-bridged intermediate enroute to the dihydroxanthone natural product nidulalin A. Reaction scope and limitations were thoroughly investigated, revealing the ability to access a multitude of synthetically challenging caged scaffolds in a two-step sequence. Photophysical studies provided key mechanistic insights on the process for formation of the novel caged scaffold.