A steam-distillation of leaves and stems of a suspected mixture of species$ of Plectranthus (Labiatae) from Springbrook yielded a little essential oil and some orange crystals, C20H2603, m.p. 166.5-167O, in 0.025% yield.The chemical and physical properties of this substance agree closely with those of the diterpene quinone dehydroroyleanone (I), first described as a constituent of the roots of Inula royleana by Edwards, Feniak, and Los.1 No depression of the mixed melting point was observed.The leucoacetate (11) shows ultraviolet absorption very similar to that of
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Gough et al. (1966) studied this question.