West African timbers. Part XX. The structure of turraeanthin, an oxygenated tetracyclic triterpene monoacetate

Abstract

Extraction of the heartwood of Turraeanthus africanus has afforded a new tetracyclic triterpene acetate, turraeanthin, C₃₂H₅₀O₅. It is a derivative of tirucalla-7,24-dienyl 3β-acetate having an oxidised side chain with an aldehyde group at C-21, a hydroxyl group at C-23, and the 24,25-double bond epoxidised. The aldehyde group forms a hemiacetal with the C-23 hydroxyl group. Turraeanthin has been converted into flindissone lactone of known structure.

The possible role of compounds such as turraeanthin in the biosynthesis of degraded tetracyclic triterpenes is discussed.