With the aim of increasing the selectivity of the 2, 2-dimethylphosphoraziridine type antitumor agents toward the intracellular site of DNA synthesis, a series of new compounds was synthesized in which the reactive bis (2, 2-di-methyl-l-aziridinyl) phosphinyl (2, 2- DMAP) group was linked through a carbamate or amide linkage to thymidine or cytosine nucleoside moieties. The 3'-and 5'-(2, 2-DMAP) carbamates of thymidine (1 and 2) were ...