Clerodane Diterpenoids from Ajuga decumbens

Abstract

A new neo-clerodane diterpene, ajugacumbin G, was isolated from Ajuga decumbens THUNB. (Labiatae), and the structure was characterized as 6α-acetoxy-4α, 17-epoxy-18-(3'-hydroxy-2'-methylenebutyryloxy)-neo-cleroda-13-en-15, 16-olide by ¹H-and ¹³C-NMR spectral study and by comparison with the known compounds of ajugacumbins A and B. Reactions to an epoxy moiety of ajugacumbin compounds with halogen acid, HX (X=Cl, Br and I) and with Jones reagent were prepared to supply some samples with different substituents at C-4 for insect antifeedant examination.