(2S,4S)-4-(((benzyloxy)carbonyl)amino)-1-(tert-butoxycarbonyl)pyrrolidine-2-carboxylic acid

3(R)-[(4(S)-(4-amino)-1-(tert-butoxycarbonyl)-2(S)-pyrrolidinylcarbonyl)amino]-2-oxo-1-pyrrolidineacetamide

3(R)-[(4(S)-((4-azidobenzoyl)amino)-1-(tert-butoxycarbonyl)-2(S)-pyrrolidinylcarbonyl)amino]-2-oxo-1-pyrrolidineacetamide