Used in solid-phase oligonucleotide synthesis, this phosphoramidite building block enables the site-specific incorporation of N2-ethylguanine into DNA strands. The DMT (dimethoxytrityl) group provides 5′-end protection during synthesis, allowing stepwise addition and coupling control. The phosphoramidite moiety ensures efficient and selective phosphite bond formation with the growing DNA chain. This modified nucleoside is particularly valuable in studying DNA damage, epigenetic regulation, and mutagenesis caused by alkylating agents. It is also employed in developing modified aptamers and functional nucleic acids with enhanced stability or binding properties.