Pyrimidine nucleoside derivatives having anti-tumor activity, their preparation and use

摘要

Compounds of formula (I): Äin which: R<1>, R<2> and R<3> are the same or different and each represents a hydrogen atom, an optionally substituted alkanoyl group or an alkenylcarbonyl group, provided that at least one of R<1>, R<2> and R<3> represents an unsubstituted alkanoyl group having from 5 to 24 carbon atoms, said substituted alkanoyl group or said alkenylcarbonyl group; and one of R4 and R5 represents a hydrogen atom and the other represents a cyano groupÜ; have valuable anti-tumour activity.