Bioinspired Semisynthesis and Structure Revisions of Chlorinated Norsesquiterpenoids Rumphellatins A-C.

The first synthesis of chlorine-containing hemiketals, rumphellatins A-C ( 1 - 3 ), previously inaccessible by means of total synthesis, was achieved starting from commercially available (-)-β-caryophyllene oxide ( 7 ). Structures of rumphellatins A ( 1 ) and C ( 3 ) were revised, while structures of rumphellatin B ( 2 ) and intermediate rumphellolide C ( 19 ) 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.