2-(2-amino-4,7-dioxo-1,8-dihydropteridin-6-yl)acetic acid

diethyl 2-acetyloxybutanedioate

ethyl 6-methoxy-4-oxo-1H-quinoline-2-carboxylate

5-氧代-2,5-二氢-1H-吡唑-3-甲酰肼

ethyl 4,5-dioxooxolane-3-carboxylate