The invention provides compounds of the formula:R1is OR11, or NR5R5’；R2is H or F；R5isH, C1-C6alkyl, OH, C(=O)R6, O(C=O)R6or O(C=O)OR6；R5´isH or C1-C6alkyl；R6is C1-C6alkyl or C3-C7cycloalkyl；R13is H, phenyl, pyridyl, benzyl, indolyl or naphthyl wherein the phenyl, pyridyl, benzyl, indolyl and naphthyl is optionally substituted with 1, 2 or 3 R22；and the other variables are as defined in the claims,which are of use in the treatment of cancer, and related aspects.本發明提供下式之化合物，R1為OR11、或NR5R5'；R2為H或F；R5為H、C1-C6烷基、OH、C(=O)R6、OC(=O)R6或OC(=O)OR6；R5'為H或C1-C6烷基；R6為C1-C6烷基或C3-C7環烷基；R13為H、苯基、吡啶基、苄基、吲哚基或萘基，其中該苯基、吡啶基、苄基、吲哚基及萘基視情況經1、2或3個R22取代；且其他變數如申請專利範圍中所定義，其係用於治療癌症，及相關態樣。
