4-溴吡啶-2,6-二羧酸二乙酯

4-methyl-3-[4-(4-oxopyridin-1-yl)phenyl]-4,5-dihydro-1H-pyridazin-6-one

4-氯-2,6-吡啶二羰基二氯

6-(Ethoxycarbonyl)-4-oxo-4H-pyran-2-carboxylic acid

4-氧代吡喃-2,6-二羧酸二乙基酯