The absolute configuration of ( - )-angolensin

Oxidation of (-)-angolensin isolated from the heartwood of Pterocarpus angolensis has yielded (-)-2-(4-methoxyphenyl)propionic acid (Ia). This establishes that the isoflavonoid, (-)-angolensin, has the R-configuration (II) and the relation between this absolute stereochemistry and that of other isoflavonoids is discussed.