N-(2-Methoxyphenyl)maleamidic acid

(Z)-3-[(2-Methoxyphenyl)carbamoyl]propenoic acid

(Z)-4-(2-Methoxyphenylamino)-4-oxo-2-butenoic acid

(Z)-4-Oxo-4-[(2-methoxyphenyl)amino]-2-butenoic acid