Structure of orientanone from Alisma orientalis, a novel sesquiterpene originating from guaiane-type carbon skeleton by isopropyl shift

A new sesquiterpene, named orientanone (), was isolated from Alisma orientalis Juzep. The structure was elucidated by various spectroscopic methods and X-ray crystallography. Orientanone has a carbon skeleton originating from a guaiane-type carbon skeleton by an isopropyl shift.