(+)-Almuheptolide-A was isolated from the methanolic extract of the powdered stem bark of Goniothalamus arvensis (1). A semisynthesis starting from (+)-altholactone (I) has also been reported. Refluxing in EtOH containing H2SO4 provided a mixture of the ethoxy derivative (-)-etharvensin (II) and the title compound. Etharvensin (II) was further converted into the title compound upon prolonged heating in H2SO4-EtOH.

(+)-Almuheptolide-A (III) was either isolated from the methanolic extract of the powdered stem bark of Goniothalamus arvensis or obtained by semisynthesis from (+)-altholactone (I). Treatment of (I) with boiling EtOH containing H2SO4 provided a mixture of the ethoxy derivative (-)-etharvensin (II) and the eight-membered-ring lactone (III). Then, acetylation of (III) with Ac2O in pyridine yielded the title diacetate ester. The (-)-etharvensin (II) can be converted into the eight member-ring lactone (III) upon prolonged heating in H2SO4 /EtOH.