Used as a key building block in medicinal chemistry, particularly in the design of bioisosteres for phenyl and other aromatic rings. Its rigid, three-dimensional structure helps improve metabolic stability, solubility, and binding selectivity in drug molecules. Commonly incorporated into pharmaceuticals to replace flat aromatic systems, enhancing pharmacokinetic properties. Widely applied in the development of CNS drugs, kinase inhibitors, and PET tracers due to its favorable polarity and ability to project substituents in defined spatial orientations. Also employed in peptide modification to increase stability and modulate conformation.