2-Butenedioic acid, 2-[5-chloro-3-(2-ethoxy-2-oxoethyl)-2,4-dioxo-1H,3H-pyrimidinyl]-, diethyl ester, (2E)- Fumaric acid, 2-[5-chloro-3-(2-ethoxy-2-oxoethyl)-2,4-dioxo- 1H,3H-pyrimidinyl]-, diethyl ester NSC704888