Dimerization of butenolide structures. A biomimetic approach to the dimeric sesquiterpene lactones (+/-)-biatractylolide and (+/-)-biepiasterolide.

The biomimetic synthesis of the bisesquiterpene lactones (+/-)-biatractylolide 1 and (+/-)-biepiasterolide 2 via dimerization of the captodative stabilized radical 8 is reported. Atractylon 7 has also been shown to be a possible intermediate during the biosynthesis of biatractylolide 1, biepiasterolide 2, atractylolide 3, and hydroxyatractylolide 4.