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 BENTH 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‐orthoquinones; 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 1H‐coupled 13C‐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.