Dimeric guaianolides and a fulvenoguaianolide from Artemisia myriantha

The aerial parts of Artemisia myriantha have afforded one new fulvenoguaianolide and four dimeric guaianolides in addition to seven known guaianolides. The structures of all the compounds were elucidated by 2D NMR. It is speculated that the dimeric guianolides are formed via Diels-Alder type reactions of fulvenoguaianolide derivatives.