This compound, 4-((tert-Butyldimethylsilyl)oxy)but-2-ynoic acid, is a specialized intermediate in organic synthesis. It features a hydroxyl group protected as a tert-butyldimethylsilyl (TBDMS) ether at the 4-position, which shields it during reactions involving the carboxylic acid or the alkyne. The conjugated alkyne moiety enables participation in metal-catalyzed coupling reactions, cycloadditions, and other transformations for building complex structures. This makes it valuable for the synthesis of pharmaceuticals, natural products, bioactive compounds, and advanced materials, where selective protection and modular assembly are essential.