[H]OC1=C2C(O[C@]3(OC([H])([H])C([H])([H])[H])C([H])([H])C(=O)C(C(=O)C([H])([H])[H])=C(O[H])[C@]23C([H])([H])[H])=C(C(O[H])=C1C(=O)C([H])([H])[H])C([H])([H])[H]