Synthesis of Oligonucleotides Containing the N 6 ‐(2‐Deoxy‐α,β‐ d ‐erythropentofuranosyl)‐2,6‐diamino‐4‐hydroxy‐5‐formamidopyrimidine (Fapy⋅dG) Oxidative Damage Product Derived from 2′‐Deoxyguanosine

N 6 ‐(2‐Deoxy‐α,β‐ d ‐erythropentofuranosyl)‐2,6‐diamino‐4‐hydroxy‐5‐formamidopyrimidine (Fapy⋅dG) is a major DNA lesion produced from 2′‐deoxyguanosine under oxidizing conditions. Fapy ⋅ dG is produced from a common intermediate that leads to 7,8‐dihydro‐8‐oxo‐2′‐deoxyguanosine (8‐OxodGuo), and in greater quantities in cells. The impact of Fapy ⋅ dG on DNA structure and function is much less well understood than that of 8‐OxodGuo. This is largely due to the significantly greater difficulty in synthesizing oligonucleotides containing Fapy ⋅ dG than 8‐OxodGuo. We describe a synthetic approach for preparing oligonucleotides containing Fapy ⋅ dG that will facilitate intensive studies of this lesion in DNA. A variety of oligonucleotides as long as 30 nucleotides are synthesized. We anticipate that the chemistry described herein will provide an impetus for a wide range of studies involving Fapy ⋅ dG.