(R)-2-Amino-4-(4-hydroxyphenyl)butanoic acid hydrobromide is a chiral, non-proteinogenic amino acid derivative. It features a phenyl ring substituted with a hydroxyl group at the para position, attached to the beta-carbon of the amino acid backbone. The compound is provided as a hydrobromide salt, which enhances its stability and solubility for synthetic applications. This compound serves as a crucial chiral building block in pharmaceutical research and development. Its primary application is as a key intermediate in the synthesis of active pharmaceutical ingredients (APIs), particularly those targeting the central nervous system. For instance, it is a vital precursor in the synthesis of (R)-(-)-Baclofen, a specific GABA_B receptor agonist used as a muscle relaxant and antispastic agent. The chiral (R)-configuration of the alpha-carbon is essential for the biological activity of the final drug molecule. The presence of both the amino acid functionality and the phenolic hydroxyl group makes it a versatile synthon for constructing more complex bioactive molecules. Its use underscores the importance of chiral intermediates in creating enantiomerically pure therapeutics to ensure efficacy and reduce side effects.