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Two novel sesquiterpene dimers, compounds 1 and 2, were isolated from the rhizome of Ligularia virgaurea, together with the six known sesquiterpenoids 3 -8. Their structures were established by physico-chemical and spectroscopic methods, especially by means of 1D-and 2D-NMR as well as HR-MS analyses. A mechanism based on a classical Diels -Alder cyclization is proposed for the formation of the dimer 1 from the precursors 8 and the quinone form of 6 (Scheme).

Extraction of roots of Patrinia rupestris (Pall.) Juss. gave a new iridoid compound, 1β,3α-diethyloxy-7-hydromethyl-4-(3-methyl-butyryloxymethyl)-cyclopenta-4(4a),7(7a)-diene[c]pyran-6-one (1), together with a known compound, (1α,4aα, 6α,7β,7aα)-[4a,5,6,7,7a-hexahydro-6,7-dihydroxy-1-(3-methyl-1-oxobutoxy) cyclopenta[c]pyran-4,7-diyl]bis(methylene) 3-methyl-butanoic acid ester (2). The structure of 1 was characterised by HRESIMS, IR, UV, 1-D NMR and 2-D NMR methods. Compound 2 was isolated from this genus for the first time.

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