6-甲氧基-5-硝基-2-吡啶羧酸

methyl 5-benzyloxycarbonylamino-6-oxo-1-hydropyridine-2-carboxylate

methyl (5S)-5-benzyloxycarbonylamino-6-oxo-1,4,5-trihydropyridine-2-carboxylate

methyl (6RS,5S)-5-benzyloxycarbonylamino-6-hydroxy-1-t-butoxycarbonyl-4,5,6-trihydropyridine-2-carboxylate

methyl (5S)-5-benzyloxycarbonylamino-6-oxo-1-t-butoxycarbonyl-4,5,6-trihydropyridine-2-carboxylate