C8-Arylamine-dG adducts of borderline carcinogens and the bladder and breast carcinogen 4-aminobiphenyl were prepared using cross-coupling chemistry. These adducts were converted into the corresponding C8-arylamine-5'-O-DMTr-2'-deoxyguanosine phosphoramidites and then used as building blocks for automated synthesis of site-specifically modified oligonucleotides. The oligonucleotides were characterized by UV melting temperature analysis, enzymatic digestion, and circular dichroism.