REVISED STRUCTURES OF CANGOROSINS, TRITERPENE DIMERS FROM MAYTENUS-ILICIFOLIA

Structures of four triterpene dimers, cangorosins, isolated from Mayte nus ilicifolia Mart., were previously reported to consist of two trite rpene units joined by an ether bond formed between the two A rings. On the basis of detailed studies of their chemical and spectroscopic dat a, including inverse-detected BD-NMR data, and comparisons with other known triterpene dimers, the structures of the cangorosins have been r evised to triterpene dimers linked by two ether bridges between the tw o A rings for cangorosin B and between the A and the B rings for the c angorosin A series (cangorosin A, isocangorosin A, and 6',7'-dihydrois ocangorosin A).