[H]O[C@@]1([H])C([H])([H])C([H])([H])C2=C([H])C(=O)[C@]([H])(C(=C([H])[H])C([H])([H])[H])C([H])([H])[C@]2(C([H])([H])[H])[C@@]1([H])C([H])([H])[H]