4-(4-Carboxybenzyl)-2H-1,4-benzoxazin-3(4H)-one4-((3-oxo-2H-benzo[b][1,4]oxazin-4(3H)-yl)methyl)benzoic acid4-[(3-Oxo-2,3-dihydro-4H-1,4-benzoxazin-4-yl)methyl]benzoic acid4-[(2,3-二氢-3-羰基-4H-1,4-苯并嗪-4-基)甲基]苯甲酸4-[(2,3-Dihydro-3-oxo-4H-1,4-benzoxazin-4-yl)methyl]benzoic acid