Synthesis and cytotoxic activity of some new 2,6-substituted purines

A seriesof twenty four acyclic unsaturated 2,6-substututed purines 5a-20b were synthesized. These compounds were evaluated for cytotoxic activity against NCI-60 DTP human tumor cell line screen at 10μMconcentration. N?-(Z)-4'-chloro-2'-butenyl-1'-yl]-2,6-dichloropurine(5a), N?-4'-chloro-2'-butynyl-1'-yl]-2,6-dichloropurine(10a), N?-(E)-2',3'-dibromo-4'-chloro-2'-butenyl-1'-yl]-6-methoxypurine(14)and N?-4'-chloro-2'-butynyl-1'-yl]-6-(4-methoxyphenyl)-purine(19)exhibited highly potent cytotoxic activity with GI?? values in the 1-5 μM range for most human tumor cell lines. Other compounds exhibited moderate activity.