2-tert-butyl 3-ethyl (1R,3R,5R)-2-azabicyclo[3.1.0]hexane-2,3-dicarboxylate is a chiral bicyclic compound featuring a rigid azabicyclo[3.1.0]hexane scaffold. This structure incorporates a fused cyclopropane ring, which imparts significant conformational constraint and three-dimensionality. The molecule is protected with a tert-butoxycarbonyl (Boc) group on the nitrogen and an ethyl ester on the carboxylic acid, making it a versatile and stable synthetic intermediate. This compound is primarily utilized as a key chiral building block in pharmaceutical research and development. Its constrained, three-dimensional structure is highly valuable for constructing complex bioactive molecules, particularly in the synthesis of drug candidates targeting the central nervous system (CNS) and other therapeutic areas. The (1R,3R,5R) stereochemistry is crucial for imparting specific biological activity and is often sought after in medicinal chemistry programs. As a bifunctional intermediate (protected amine and ester), it serves as a precursor for further synthetic elaboration. It is commonly used to introduce the rigid 2-azabicyclo[3.1.0]hexane motif into larger molecular architectures, a feature known to improve metabolic stability and receptor binding selectivity in drug molecules.