Convergent Synthesis of Kibdelone C

Abstract

The synthesis of kibdelone C, a polycyclic natural xanthone isolated from a soil actinomycete, was achieved through a convergent approach. A 6π-electrocyclization was applied to construct the highly substituted dihydrophenanthrenol fragment (B–C–D ring). InBr3-promoted lactonization was employed to build the isocoumarin ring, which served as a common precursor for the formation of isoquinolinone ring (A–B ring). A key DMAP-mediated oxa-Michael/aldol cascade reaction was developed to install the tetrahydroxanthone fragment (E–F ring). This approach provides a new solution to prepare its derivatives and structurally related natural products.