dimethyl 5-hydroxy-6-methylpyridine-3,4-dicarboxylate

diethyl 5-hydroxy-6-methylpyridine-3,4-dicarboxylate

乙基3-氨基-5-氰基-2-甲基异烟酸酯

3-氨基-6-氯-5-氰基-2-甲基异烟酸乙酯

2-甲基-3-羟基-4-羧基-3-羟甲基吡啶