(1R,3R,5R)-2-(tert-Butoxycarbonyl)-2-azabicyclo[3.1.0]hexane-3-carboxylic acid is a chiral bicyclic amino acid derivative featuring a rigid azabicyclo[3.1.0]hexane scaffold. This compound contains both a carboxylic acid and a tert-butoxycarbonyl (Boc)-protected secondary amine, making it a versatile building block for the introduction of constrained, three-dimensional structural motifs. This intermediate is primarily utilized in pharmaceutical research and development for the synthesis of active pharmaceutical ingredients (APIs). Its key application is as a key chiral synthon in the preparation of novel antiviral drugs, particularly those targeting hepatitis C virus (HCV). The constrained bicyclic structure is designed to mimic proline but with altered conformational and electronic properties, which can enhance binding affinity, metabolic stability, and selectivity in drug candidates. It serves as a critical component in the synthesis of complex molecules like glecaprevir, a protease inhibitor used in combination therapies. The compound is commercially available as a high-purity building block from suppliers specializing in advanced pharmaceutical intermediates. Its synthesis and use require standard handling procedures for amino acid derivatives and Boc-protected amines.