4-氧代吡喃-2,6-二羧酸二乙基酯

Diethyl 4-hydroxy-2,6-pyridinedicarboxylate

diethyl 3,5-dibromo-4-oxopyran-2,6-dicarboxylate

二氢-2H-吡喃-4(3h)-酮 肟