Studies on the chemical constituents of Chinese azalea——I.The structure of rhodomollein-I,a new toxic diterpenoid

Two unknown toxic diterpenoids, rhodomollein-I and rhodomollein-II, and the known rhodojaponin-III, have been isolated from Chinese azalea (Ericaceae, Rhododendron molle G. Don). rhodomollein-I, C20H32O6, colorless thin needles, [α]D20 −6.65 (c 3.76 × 10−2, EtOH), m. p. 241–242.5 °C. Its structure has been established as 1 through spectral analysis of 13C NMR, 1H NMR, MS, IR and UV. Moreover, its stereostructure was unambiguously identified from the different threshold level line of 1H-1H NOESY.