(S)-6-(tert-Butoxycarbonylamino)-2-[[[(9H-fluoren-9-yl)methoxy]carbonyl]amino]hexanoic acid-13C6; S)-2-[[[(9H-Fluoren-9-yl)methoxy]carbonyl]amino]-6-(tert-butoxycarbonylamino)hexanoic acid-13C6; S)-6-[(tert-Butoxycarbonyl)amino]-2-[[[(9H-fluoren-9-yl)methoxy]carbonyl]amino]hexanoic acid-13C6; Fmoc-L-LS (Boc)-OH-13C6; Fmoc-L-LS(Boc)-OH-13C6; N-α-(Fmoc)-N-ε-(t-boc)-L-LSine-OH-13C6; N-α-Fluorenylmethoxycarbonyl-N-ε-tert-butoxycarbonyl-L-lSine-13C6; SC 334302-13C6; Nα-(9-Fluorenylmet