[H]OC1=C2C(O[C@]3(C([H])([H])[H])[C@]([H])(O[H])[C@@]([H])(C([H])([H])[H])C([H])([H])[C@@]([H])(O[H])[C@@]3([H])C2=O)=C([H])C([H])=C1[H]