(S)-2-Aminobutyramide-d3 (hydrochloride) is the deuterium labeled (S)-2-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-5-(tert-butoxy)-5-oxopentanoic acid[1].
References
[1] Russak EM, et al. Impact of Deuterium Substitution on the Pharmacokinetics of Pharmaceuticals. Ann Pharmacother. 2019;53(2):211-223. DOI:10.1080/02688697.2018.1500521