Preparation of a ε-caprolactonic diterpenoid derivate by unexpected oxidative cleavage/lactonization of 2-oxoaustroeupatol

Abstract

From aerial parts of Austroeupatorium inulifolium was isolated the ent-nor-furano triol labdane austroeupatol 1. The compound 1 was treated with IBX showing an unexpected selectivity at the potentially oxidizable sites of the substrate yielding the 2-oxoaustroeupatol (2) and 2,19-dioxoaustroeupatol (3). The treatment of 2 with sodium periodate yields a heterocyclic derivative (ε-caprolactone derivate 4) formed by oxidative cleavage and unexpected intramolecular attack of the hydroxymethylene (C-19) oxygen to the ketonic carbon (C-2). A plausible mechanistic pathway for the obtention of compound 4 is proposed. Graphical Abstract

Enzymatic Synthesis of Austroeupatol Esters with Enhanced Antiprotozoal Activity

“…King & H. Rob. (Asteraceae), an invasive shrub that is mainly distributed in the warm areas of South America and South Asia. , The antibacterial activity of this natural compound and its semisynthetic derivatives has previously been studied; , however, no other biological activities related to austroeupatol or any semisynthetic derivatives have been reported so far. Thus, considering that austroeupatol is obtained in high yield from an easily available natural source and taking into account the antiprotozoal activity of some labdane diterpenoids, we aimed to synthesize austroeupatol esters by enzymatic catalysis and assess the antiprotozoal activity of this natural compound and its derivatives against Trypanosoma cruzi and Leishmania infantum .…”