(R)-3-tert-Butoxycarbonylamino-pyrrolidine-1-carboxylic acid 4-nitro-phenyl ester

((R)-1-{(S)-3-[Methyl-(4'-trifluoromethyl-biphenyl-4-carbonyl)-amino]-pyrrolidine-1-carbonyl}-pyrrolidin-3-yl)-carbamic acid tert-butyl ester