Drüsenfarbstoffe aus Labiaten: Ecklonochinone A und B, zwei neuartige Dibenzo‐ p ‐dioxin‐ o ‐chinone aus Plectranthus ecklonii B ENTH

Leaf‐gland Pigments from Labiatae: Ecklonoquinones A and B, Two Novel Dibenzo‐ p ‐dioxine‐ o ‐quinones from Plectranthus ecklonii B ENTH From the leaf‐glands of the above mentioned labiate the following compounds have been isolated and their structures established: ecklonoquinone A ( 1 ) and ecklonoquinone B ( 2 ), two novel isomeric dibenzo‐ p ‐dioxine‐ ortho quinones; 2 ( S )‐5,4′‐dihydroxy‐6,7‐dimethoxyflavanone ( 8 ); the already known flavone cirsimaritin ( 9 ) and the diterpenoid p ‐quinomethane parvifloron F ( 10a ). The spectral data of the dimeric p ‐menthanes 1 and 2 are very similar, and only analysis of the 1 H‐coupled 13 C‐NMR.‐spectra lead to structures 1 and 2 , respectively. Our tentative assignment of these structures to the individual molecules is based on a comparison of the spectral data with the synthetic compound 7 .