Synthesis, SAR, and preliminary mechanistic evaluation of novel antiproliferative N6,5′-bis-ureido- and 5′-carbamoyl-N6-ureidoadenosine derivatives

R = Phenyl, p-chlorophenyl, p-iodophenyl, m-iodophenyl, p-nitrophenyl, p-methoxyphenyl, benzyl, propyl, hexyl, cyclohexyl.