The synthesis of C5 linked uracil dimers was carried out according to a model developed in order to bind adenine in DNA. N1-Alkylated uracil derivatives were synthesized from isoorotic acid (uracil-5-carboxylic acid) or thymine. The carboxylic acid derivatives were condensed with diamines in order to produce dimeric compounds or with monoamines in order to obtain reference monomeric compounds. Some of the derivatives, in particular the uracil dimers, showed antiproliferative and erythroid differentiation induction properties towards human chronic myelogenous leukemia K562 cells, thus indicating that these compounds could represent a new class of drugs useful for the development of antitumor therapy based on the ability to induce terminal differentiation.