methyl 1,6-dihydro-6-oxo-2-pyrazinecarboxylate 4-oxide

甲胺

methyl 6-chloro-2-pyrazinecarboxylate 4-oxide

6-hydroxymethyl-2(1H)-pyrazinone 4-oxide

4-氧代-6-氧代-1H-吡嗪-4-鎓-2-羧酸