3,4-噻吩二甲酸

ethyl 2-(2-methyl-6-oxo-1H-pyrimidin-5-yl)acetate

2-(acetamidomethylidene)butanedioic acid

(2,4-二氧代-1,2,3,4-四氢嘧啶-5-基)乙酸

6-氧代-1,6-二氢吡嗪-4-羧酸乙酯