Arylamines are mutagens and carcinogens and are thought to initiate tumors by forming adducts with DNA. The major adducts are C 8-guanyl, and we have previously suggested a role for guanyl-N 7 intermediates in the formation process. N 7-Aminoguanosine (Guo) was synthesized and characterized, with the position of the NH2 at N7 established by two- dimensional rotating frame Overhauser enhancement NMR spectroscopy. In DMF, N 7- ...