CCC(=O)O[C@@H]1C(=O)[C@@]2(C)[C@@H](CC[C@H]3C4=C(CCC=C(C)C)C(=O)O[C@H]4C[C@@]32C)[C@@]2(C)C=CC(=O)[C@@H](C)[C@H]12	6-O-propionyl-6,16-O-dideacetylhelvolic acid 21,16-lactone