Used in solid-phase oligonucleotide synthesis, this phosphoramidite building block enables the site-specific incorporation of modified uridine residues into DNA strands. The cyanoethylthio group acts as a functional handle for downstream conjugation, such as attaching fluorophores, biotin, or other reporter molecules via thiol-reactive chemistry. Its DMT (dimethoxytrityl) protection allows for efficient monitoring of coupling efficiency during synthesis, while the phosphoramidite group ensures high coupling yields on DNA synthesizers. Commonly applied in the development of probes, primers, and modified antisense oligonucleotides for research, diagnostics, and therapeutic applications.