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