Pentanoic acid, 2-hydroxy-4-oxo-, ethyl ester

ethyl 3-methyl-4,5-dihydro-1,2-oxazole-5-carboxylate

乙酰丙酸

6-methyl-3-oxo-2,3-dihydro-pyridazine-4-carbonitrile

乙基(4E)-4-(氨基甲酰异二氮烯)戊酸酯