Biomimetic synthesis of Sinularia meroterpenoids and photochemical reactivity of capillobenzopyranol

Abstract

Motivated by a biosynthetic proposal which suggests a chemical relationship between capilloquinol and capillobenzopyranol, our studies report the first synthesis of their probable biogenetic precursors, furanoquinol and furanoquinone. A bioinspired cascade using an ortho-quinone methide intermediate derived from furanoquinone was attempted to construct the spirocyclic moiety of capilloquinol but instead led to the formation of capillobenzopyranol via an oxa-6π-electrocyclisation. Subsequent photochemical transformations of capillobenzopyranol resulted in a formal 1,3-hydrogen shift followed by intramolecular [2 + 2]-cycloaddition to construct an unusual 6–6–6–4 fused polycyclic compound.