ethyl 4-hydroxy-2-methyl-6-oxopyran-3-carboxylate

4,6-二甲基-2-氧-2H-吡喃-5-甲酸乙酯

7-羟基-5-氧代-1,2,3,5-四氢氮茚-8-甲酸乙酯

3-羟基-1H-PHENALEN-1-酮

3,5-庚烷二酮