N2-Phenylacetyl-2′-deoxyguanosine can be prepared in high yield and exceptional purity by pretreating phenylacetyl chloride with 1-hydroxybenzotriazole and adding the thus formed adduct to the tris[trimethylsilyl] ether derivative of 2′-deoxyguanosine. Subsequently, the crystalline product can be treated with 9-chloro-9-phenylxanthene which results in a crystalline material suitable for use in oligodeoxyribonucleotide synthesis procedures.