abstract |
Compounds having the following formula:wherein: R1 is for example, H;C1-24 alkyl;C2-24 alkenyl;C6-24aryl;C5-20 heteroaromatic ring; orC3-20 non aromatic ring; R2 is a purine of pyrimidine group; or a pharmaceutically acceptable salt thereof, are useful in treating a patient having cancer. |