Used as a key intermediate in the synthesis of pharmaceuticals, particularly in the development of proteolysis-targeting chimeras (PROTACs). It serves as a linker component that connects target-binding ligands to E3 ubiquitin ligase ligands, enabling targeted protein degradation. Its rigid, semi-cyclic structure provides stability and optimal spatial orientation, enhancing the efficiency and selectivity of the resulting degraders. Widely applied in research for cancer therapeutics and neurodegenerative disease drug development.