5-Fluorouracil derivatives

A compound of the formula ##STR32## wherein R.sup.1 is C.sub.6 to C.sub.10 aryl or C.sub.6 to C.sub.10 aryl substituted by halogen, C.sub.1 to C.sub.5 alkyl, C.sub.1 to C.sub.5 haloalkyl, C.sub.1 to C.sub.5 alkoxy, nitro, cyano or carboxy,

• R.sup.2 is C.sub.1 to C.sub.30 straight or branched chain alkyl, C.sub.3 to C.sub.11 cyclic alkyl wherein the cyclic moiety is 3 to 6 membered, adamantyl, C.sub.6 to C.sub.10 aryl or C.sub.6 to C.sub.10 aryl substituted by halogen, C.sub.1 to C.sub.5 alkyl, C.sub.1 to C.sub.5 haloalkyl, C.sub.1 to C.sub.5 alkoxy, nitro, cyano or carboxy, and
• R.sup.3 and R.sup.4 are the same or different and each is hydrogen or lower alkyl.