Boc-(R)-3-Amino-4-(4-chlorophenyl)butyric acid is a chiral amino acid derivative featuring a Boc-protected amine group and a carboxylic acid functional group. Its molecular structure contains a 4-chlorophenyl substituent, making it a valuable non-natural, phenylalanine-like chiral building block. This compound is a critical chiral intermediate in the synthesis of active pharmaceutical ingredients (APIs). Its primary and well-documented application is in the synthesis of (R)-Baclofen, a selective GABA_B receptor agonist used as a muscle relaxant and antispastic agent for treating conditions like multiple sclerosis and spinal cord injuries. The (R)-enantiomer is the pharmacologically active form. The Boc-protected amino acid serves as a key precursor, allowing for controlled peptide coupling or further functionalization while preserving the crucial chiral center during synthetic steps. As a protected β-amino acid, it is utilized in medicinal chemistry research for constructing peptidomimetics and other bioactive molecules targeting the central nervous system. The compound is typically handled under standard laboratory conditions, and its quality is crucial for ensuring the enantiopurity of the final drug substance.