[H]C([H])=C(C([H])([H])[H])[C@]1([H])C([H])([H])C2=C(C(=O)C([H])([H])C([H])([H])[C@@]2(C([H])([H])[H])C([H])([H])C1([H])[H])C([H])([H])[H]