| abstract |
The invention provides a compound of formula (I) n n n n n n n n n n wherein n B is a nucleobase; n U is O or S; n R x is —OC(═O)R y , —OC(═O)CH(R y )NH 2 , —OCH 2 OC(═O)R y ; n R y is optionally substituted alkyl or alkenyl or the side chain of a natural or unnatural amino acid n R 1 is H, or optionally substituted phenyl, benzyl, naphthyl, pyridyl or indolyl, or n R x and R 1 together define a bond thus forming a cyclic phosphate; n R 2 and R 2′ together define the side chain of a natural or unnatural amino acid; n R 3 is optionally substituted alkyl, cycloalkyl, phenyl or benzyl; n and pharmaceutically acceptable salts and compositions thereof n which are useful in the treatment of cancer, especially leukemias. |