4-(Carboxymethyl)-2H-1,4-benzoxazin-3(4H)-one2-(3-oxo-2H-benzo[b][1,4]oxazin-4(3H)-yl)acetic acid2,3-二氢-3-羰基-4H-1,4-苯并恶嗪)-4-乙酸3-Oxo-2,3-dihydro-4H-1,4-benzoxazine-4-acetic acid2,3-Dihydro-3-oxo-4H-1,4-benzoxazine-4-acetic acid(3-oxo-2,3-dihydro-4H-1,4-benzoxazin-4-yl)acetic acid