(9H-fluoren-9-yl)methyl (2R,2'S,4R,9a'S)-2'-isobutyl-3',5-dioxo-4-(((2,2,2-trichloroethoxy)carbonyl)amino)-2',3',4,5-tetrahydro-3H-spiro[furan-2,9'-imidazo[1,2-a]indole]-1'(9a'H)-carboxylate

(9H-fluoren-9-yl)methyl (2R,2'S,4R,9a'S)-2'-methyl-3',5-dioxo-4-(((2,2,2-trichloroethoxy)carbonyl)amino)-2',3',4,5-tetrahydro-3H-spiro[furan-2,9'-imidazo[1,2-a]indole]-1'(9a'H)-carboxylate

2,2,2-trichloroethyl ((2R,2'S,4R,9a'R)-2'-isobutyl-3',5-dioxo-1',2',3',4,5,9a'-hexahydro-3H-spiro[furan-2,9'-imidazo[1,2-a]indol]-4-yl)carbamate

(S)-9-((R)-2-{2-[(S)-2-(9H-Fluoren-9-ylmethoxycarbonylamino)-propionylamino]-benzoylamino}-2-methoxycarbonyl-ethyl)-2-methyl-3-oxo-2,3-dihydro-imidazo[1,2-a]indole-1-carboxylic acid benzyl ester

(S)-9-((R)-2-Amino-2-methoxycarbonyl-ethyl)-2-methyl-3-oxo-2,3-dihydro-imidazo[1,2-a]indole-1-carboxylic acid benzyl ester