West African timbers. Part XXII. The diterpenes of Oxystigma oxyphyllum Harms

Abstract

Five diterpene acids have been isolated from the fresh wood of Oxystigma oxyphyllum Harms. Four of them belong to the eperuane series while the fifth is of the antipodal labdane series. They are eperuic acid, Δ⁷-eperuic acid, eperua-7,13-dien-15-oic acid, and copalic acid and its enantiomer labda-8(20), 13-dien-15-oic acid. This is the first example of the co-occurrence of the two antipodal series.