Bioinspired Semisynthesis and Structure Revisions of Chlorinated Norsesquiterpenoids Rumphellatins A–C

The first synthesis of chlorine-containing hemiketals, rumphellatins A-C (<b>1</b>-<b>3</b>), previously inaccessible by means of total synthesis, was achieved starting from commercially available (-)-β-caryophyllene oxide (<b>7</b>). Structures of rumphellatins A (<b>1</b>) and C (<b>3</b>) were revised, while structures of rumphellatin B (<b>2</b>) and intermediate rumphellolide C (<b>19</b>) were confirmed. The study expands availability of exotic norsesquiterpenoids for profiling their biological activity as well as facilitates the elucidation of biosynthetic pathways of their formation.