2-Butenedioic acid, (Z)-, 2-(1,2,3,4-tetrahydro-2,4-dioxo-3-propynyl-1-pyrimidinyl)-, diethyl ester Maleic acid, 2-(1,2,3,4-tetrahydro-2,4-dioxo-3-propynyl-1-pyrimidinyl)-, diethyl ester NSC693983 Pyrimidine-2,4(1H,3H)-dione, 1-[1,2-bis(ethoxycarbonyl)ethenyl]-3-propynyl-, (Z)- Uracil, 1-[1,2-bis(ethoxycarbonyl)ethenyl]- 3-propynyl-, (Z)-