acetic acid 3S-{5R-(3'-{4S-acetoxy-1-[2S-(2S-methylaminopropionylamino)butyryl]pyrrolidin-2R-ylmethyl}-6,6'-difluoro-1H,1'H-[2,2']biindol-3-ylmethyl)-1-[2S-(2S-methylaminopropionylamino)butyryl]pyrrolidin}-3-yl ester

4-(tert-butyldimethylsilanyloxy)-2-(6-fluoro-1H-indole-3-carbonyl)pyrrolidine-1-carboxylic acid benzyl ester

[2S-(6-fluoro-1H-indole-3-carbonyl)-4R-hydroxypyrrolidin-1-yl]carboxylic acid benzyl ester

[2S-(6-fluoro-1H-indole-3-carbonyl)-4S-(4'-nitrobenzoyloxy)pyrrolidin-1-yl]carboxylic acid benzyl ester

[2S-(6-fluoro-1H-indole-3-carbonyl)-4S-hydroxypyrrolidin-1-yl]carboxylic acid benzyl ester