Methyl 4-((tert-butyldimethylsilyl)oxy)but-2-ynoate is a specialized intermediate in organic synthesis, featuring a tert-butyldimethylsilyl (TBDMS) protecting group on the terminal hydroxyl of a but-2-ynoate ester. This protection shields the alcohol during multi-step reactions, enabling selective functionalization of the alkyne and ester groups in the construction of complex molecules. It is commonly employed in pharmaceutical and agrochemical research for synthesizing alkynes, bioactive compounds, and natural product analogs, owing to its stability across diverse reaction conditions and compatibility with orthogonal deprotection strategies.