4-甲基-2-氧代-2,3-二氢-1H-咪唑-5-羧酸乙酯

5-甲基-1,2,3-噁二唑-4-羧酸乙酯

(Z)-3-methyl-4-oximinoisoxazol-5(4H)-one

3-(hydroxyamino)-2-nitrosobut-2-enoic acid

1,4-diethyl-5-methylpyrrole-2,3-dicarboxylic acid