(4R)-4-(Aminomethyl)pyrrolidin-2-one is a chiral, non-proteinogenic amino acid derivative featuring a pyrrolidin-2-one (γ-lactam) ring system with an aminomethyl substituent at the 4-position. Its CAS number is 1407997-81-2. This compound is a versatile and valuable building block in medicinal chemistry and peptide research. Its primary application is as a key intermediate in the synthesis of pharmaceutical compounds, particularly those targeting the central nervous system. The γ-lactam scaffold is a privileged structure in drug discovery, often used to mimic peptide bonds and improve metabolic stability and bioavailability. The chiral (R)-configuration and the functional groups make it suitable for constructing constrained peptide analogs and peptidomimetics. It serves as a precursor for various bioactive molecules and is frequently employed in the development of protease inhibitors and other therapeutic agents. As a chiral, functionalized heterocycle, it is also a valuable reagent in the synthesis of complex natural products and in the exploration of novel chemical space for drug candidates. Its utility extends to the preparation of specialized amino acids for peptide-based bioconjugates and biochemical probes.