Two Novel ent‐Kaurene Diterpenoids from Isodon rubescens

A novel 20‐nor‐ent‐kaurene diterpenoid, rubescensin N ( 1 ), and a new 7,20‐epoxy‐ent‐kaurene diterpenoid, rubescensin O ( 2 ), along with the seven known diterpenoids rabdoternins A–F and xerophilusin N, were isolated from Isodon rubescens collected in Jiyuan prefecture, Henan Province, China. Their structures were established by extensive spectroscopic analysis. Compound 1 is the first example of a naturally occurring 20‐nor‐ent‐kaurene diterpenoid from the Isodon genus plants.