Patent ID: 7825103

Claim:
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 R 1 and R 2 represents 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 3 )(R 4 )(R 5 )Si—, and the other represents a group represented by (R 6 )(R 7 )(R 8 )Si—, or R 1 and R 2 together form a 6-membered cyclic group represented by —Si(R 9 )(R 10 )—; R 3 , R 4 , R 5 , R 6 , R 7 , and R 8 each represent a substituted or non-substituted C1-C10 linear or branched alkyl group, a substituted or non-substituted C3-C6 cycloalkyl group, a substituted or non-substituted C6-C14 aryl group, or a substituted C1-C6 alkyl group which has been substituted by one or two C6-C14 aryl groups, wherein the one or two C6-C14 aryl groups are optionally substituted by a substituent selected from the group consisting of a C1-C3 linear or branched alkyl group, a hydroxyl group, a C1-C6 linear or branched alkoxy group, an amino group, a halogen atom, a cyano group, and a nitro group; and R 9 and R 10 each represent a substituted or non-substituted C1-C6 linear or branched alkyl group.