Boc-(R)-2-thienylglycine is a protected derivative of the unnatural amino acid (R)-2-thienylglycine, featuring a tert-butoxycarbonyl (Boc) protecting group on the amino terminus. It serves as a key building block in solid-phase peptide synthesis, enabling the incorporation of the thienylglycine residue into peptide chains with high stereochemical purity. This compound is essential in pharmaceutical development for creating modified peptides with enhanced properties, such as improved stability or biological activity, and in research exploring novel peptide structures for drug discovery.