Three New Diterpenoids from Rabdosia lophanthoides var. gerardiana

Abstract Three new diterpenoids, together with three known ones, were isolated from the air‐dried whole herbs of Rabdosia lophanthoides var. gerardiana. The structures of the new diterpenoids were established as 3,4‐dihydro‐11‐hydroxy‐10‐(1‐hydroxy‐1‐methylethyl)‐2,2,6‐trimethylnaphtho[1,8‐ bc ]oxocin‐5(2 H )‐one ( 1 ), 11,12,15‐trihydroxyabieta‐5,8,11,13‐tetraen‐7‐one ( 2 ), (2 R ,3 S ,4 S ,4a R ,8 S ,9a S ,13a S ,16a S )‐3,4,4a,8,9,9a,10,11,12,13,14,16a‐dodecahydro‐2‐(hydroxymethyl)‐6,6,10,10‐tetramethyl‐2 H ‐benzo[4,5]cyclohepta[1,2‐ h ]pyrano[2,3‐ b ][1,4]benzodioxepine‐3,4,8,13a,15(6 H )‐pentol ( 3 ) by spectroscopic methods, including extensive 1D‐ and 2D‐NMR analyses. The structures of the known compounds were identified by comparison of their physical and spectroscopic data with those reported in the literature.