Novel α-methyldeoxybenzoins from the heartwood of Pterocarpus angolensis D.C.: absolute configuration and conformation of the first sesquiterpenylangolensis, and X-ray crystal structure of 4-O-α-cadinylangolensin

The known 2,4-dihydroxy-4′-methoxy-α-methyldeoxybenzoin, (αR)-angolensin, is accompanied by the novel (αS)-4-O-methylangolensin and a unique epimeric pair comprising (αR,1″R,4″S,4″aR,8″aR)-4-O-α-cadinylangolensin and (αR,1″S,4″S,4″aR,8″aR)-4-O-T-cadinylangolensin in the heartwood of Pterocarpus angolensis D.C. The absolute configuration and conformation of the former was determined by X-ray analysis.Bis-(2-ethylhexyl) phthalate accompanies the above metabolites.