Pyrimidine nucleoside compound or its salt

Abstract

Provided is a pyrimidine nucleoside compound represented by the following formula (1): or a pharmaceutically acceptable salt thereof, wherein one of X and Y represents a cyano group, and the other represents a hydrogen atom; one of Rand Rrepresents a hydrogen atom, a carbonyl group having a C1-C6 alkyl group which has been mono-substituted by an amino group, or a group represented by (R)(R)(R)Si—, and the other represents a group represented by (R)(R)(R)Si—, or Rand Rtogether form a 6-membered cyclic group represented by —Si(R)(R)—; R, R, R, R, R, and Reach represent a C1-C10 linear or branched alkyl group which may have a substituent, a C3-C6 cycloalkyl group which may have a substituent, a C6-C14 aryl group which may have a substituent, or a C1-C6 alkyl group which has been substituted by one or two C6-C14 aryl groups and which may have a substituent; and Rand Reach represent a C1-C6 linear or branched alkyl group which may have a substituent. The pyrimidine nucleoside compound of formula (1) or a pharmaceutically acceptable salt thereof exhibits a potent antitumor effect and is therefore useful as a therapeutic agent for preventing or treating a tumor.