(E)-3-(3,4-dihydroxy-5-nitrophenyl)-2-(piperidine-1-carbonyl)acrylonitrile;(?E)-?-[(3,4-Dihydroxy-5-nitrophenyl)methylene]-?-oxo-1-piperidinepropanenitrile;Entacapone EP Impurity H
(E)-3-(3,4-dihydroxy-5-nitrophenyl)-2-(piperidine-1-carbonyl)acrylonitrile;(?E)-?-[(3,4-Dihydroxy-5-nitrophenyl)methylene]-?-oxo-1-piperidinepropanenitrile;Entacapone EP Impurity H