Teupestalin

Although quite rare, there are a few examples with a hydroxyl group or an ether fonction at C-10. Teupestalin A (108) is one example isolated from T. pestalozzae [50], the structure of the compound was established by NMR spectral data including spin-decoupling and NOE experiments. 

The P-configuration assigned to this tertiary hydroxyl group in teupestalin A (108) was supported by the very deshielded resonance of one of the C-11 methylene protons [H-1 la (pro-S), 8 3.47 dd, J= 1.5 and 3.7 Hz] which is close to the lOP-hydroxyl group, and by comparison of the NMR spectral data of 113 and 114 (Table 13). Since the observed differences in the chemical shifts of the C-8 [A8 = 8(1)- 8(3), -6.2 ppm] and C-11 (A8-7.7) y-carbons were only compatible with a y-gauche arrangement [66], whereas for a 10a-hydroxyl substituents, smaller shielding effects are expected on these carbon atoms, at least on C-11 (y-trans carbon) [67]. 

The bicyclic diterpene dactylomelol has been isolated from the shell-less mollusc Aplysia dactylomela [109]. Teupestalin B is a constituent of Teucrium pestalozzae [110]. 1,4-Epoxy-13-dolastene (Fig. 8) has been isolated from a.Dictyota sp. brown alga [111],... 

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