5-fluorouracil, 2'-deoxy-5-fluorouridine and 1-carbomoyl-5-fluorouracil compounds

There are diclosed a 5-fluorouracil derivative represented by the formula (1): wherein A represents a group represented by wherein R represents a hydrogen atom or OR group, R , R and R may be the same or different and each represents a hydrogen atom or a group represented by the following formula (2): wherein R represents an acyl group, R represents a hydrogen atom, a straight or branched alkyl group, a cycloalkyl group, an aralkyl group, a lower alkenyl group or a phenyl group, and n is an integer of 0 to 6, provided that at least one of R , R and R is a group represented by the formula (2), and the case wherein R and R are both hydrogen atoms is excluded, R represents a group represented by the formula (2), and X represents an alkylene group or a cycloalkylene group, and an antitumor agent containing the same as an active ingredient.