Revised Structure of Antidesmone, an Unusual Alkaloid from Tropical Antidesma Plants (Euphorbiaceae)

Abstract The structure of antidesmone, an alkaloid from Antidesma membranaceum Mull. Arg. and A. venosum E. Mey. (Euphorbiaceae), was revised to be ( S )-4,8-dioxo-3-methoxy-2-methyl-5- n -octyl-1,4,5,6,7,8-hexahydroquinoline [( S )- 2 ], not the isoquinoline derivative 1 , as assumed previously. The revision was initiated by biosynthetic feeding experiments of one of our groups.