2-(FMoc-aMino)-2-(1-Boc-4-piperidyl)acetic Acid 4-[2-Carboxy-1-(9H-fluoren-9-ylmethoxycarbonylamino)-ethyl]-piperidine-1-carboxy 4-[Carboxy-(9H-fluoren-9-ylmethoxycarbonylamino)-methyl]-piperidine-1-carboxylic a-(Fmoc-amino)-N-Boc-4-piperidineacetic acid 2-((((9H-Fluoren-9-yl)methoxy)carbonyl)amino)-2-(1-(tert-butoxycarbonyl)piperidin-4-yl)acetic acid 2-{1-[(tert-butoxy)carbonyl]piperidin-4-yl}-2-({[(9H-fluoren-9-yl)methoxy]carbonyl}amino)acetic acid 4-Piperidineacetic acid, 1-[(1,1-dimethylethoxy)carbonyl]-α-[[(9H-fluoren-9-ylmethoxy)carbonyl]amino]- 2-(9H-fluoren-9-ylmethoxycarbonylamino)-2-[1-[(2-methylpropan-2-yl)oxycarbonyl]piperidin-4-yl]acetic acid