Two Sideritis species afforded eleven kaurene and one beyerene diterpenes. Structures of the compounds from Sideritis sipylea} were elucidated as linearol (1), 7-epicandicandiol (2), sideridiol (3), siderol (4), isolinearol (5), isosidol (6) and epoxyisolinearol (7). Linearol was treated with m -chloroperbenzoic to afford its analogues ent-3b ,7a ,17-trihydroxy-18-acetoxykaur-15-ene (1a) and ent}-7a ,17,18-trihydroxy-3b -acetoxykaur-15-ene (1b) as new compounds. From the second species, Sideritis dichotoma, the kaurenes sideridiol (3) siderol (4), ent-7a ,18-dihydroxy-15b ,16b -epoxykaurane (8)}, ent}-7a -acetoxy,18-hydroxy-15b ,16b -epoxykaurane (9), ent-7a -acetoxy-15,18-dihydroxy-kaur-16-ene (10), ent-7a ,15,18-trihydroxykaur-16-ene (11) and the beyerene ent-7a ,18-dihydroxybeyer-15-ene (12) were isolated. Structural elucidation is based on NMR techniques and mass spectrometer analyses.

Two Sideritis species afforded eleven kaurene and one beyerene diterpenes. Structures of the compounds from Sideritis sipylea} were elucidated as linearol (1), 7-epicandicandiol (2), sideridiol (3), siderol (4), isolinearol (5), isosidol (6) and epoxyisolinearol (7). Linearol was treated with m -chloroperbenzoic to afford its analogues ent-3b ,7a ,17-trihydroxy-18-acetoxykaur-15-ene (1a) and ent}-7a ,17,18-trihydroxy-3b -acetoxykaur-15-ene (1b) as new compounds. From the second species, Sideritis dichotoma, the kaurenes sideridiol (3) siderol (4), ent-7a ,18-dihydroxy-15b ,16b -epoxykaurane (8)}, ent}-7a -acetoxy,18-hydroxy-15b ,16b -epoxykaurane (9), ent-7a -acetoxy-15,18-dihydroxy-kaur-16-ene (10), ent-7a ,15,18-trihydroxykaur-16-ene (11) and the beyerene ent-7a ,18-dihydroxybeyer-15-ene (12) were isolated. Structural elucidation is based on NMR techniques and mass spectrometer analyses.