SESQUITERPENE LACTONES AND OTHER CONSTITUENTS OF MIKANIA-RIMACHII AND MIKANIA-MICROPTERA

Extraction of the aerial parts of Mikania rimachii afforded a new dihydrooxepine type elemadienolide, a rare triterpene, 3',4-dihydroxy-3-methoxypropiophenone, and various common plant constituents. The aerial parts of Mikania microptera furnished four new dihydrooxepine type elemadienolides, seven new melampolides, a new nerolidol derivative as well as nerolidol itself, 5-hydroxymethyl-2-furfuraldehyde and various common plant constituents. Structures of the new substances were investigated by high field NMR techniques and chemical transformations. In the case of one of the melampolides, the structure was confirmed by an X-ray analysis. The stereochemistry of the biological divinyloxirane dihydrooxepine rearrangement is discussed.