(2S,4R)-4-(tert-Butyl-dimethyl-silanyloxy)-2-[3-(2-hydroxy-ethyl)-thiazolidin-2-yl]-pyrrolidine-1-carboxylic acid 4-nitro-benzyl ester

(2S,4S)-4-Mercapto-2-(3-methyl-thiazolidin-2-yl)-pyrrolidine-1-carboxylic acid 4-nitro-benzyl ester

(2S,4S)-2-(3-Isopropyl-thiazolidin-2-yl)-4-mercapto-pyrrolidine-1-carboxylic acid 4-nitro-benzyl ester

(2S,4S)-2-[((R)-4-hydroxymethyl)thiazolidin-2-yl]-4-mercapto-1-(p-nitrobenzyloxycarbonyl)pyrrolidine

(2S,4S)-4-Mercapto-2-(3-methanesulfonyl-thiazolidin-2-yl)-pyrrolidine-1-carboxylic acid 4-nitro-benzyl ester