(2S,4R)-4-Acetylsulfanyl-pyrrolidine-1,2-dicarboxylic acid 2-(4-methoxy-benzyl) ester 1-(4-nitro-benzyl) ester

(2S,4R)-2-((3R,4R)-3,4-Dihydroxy-pyrrolidine-1-carbonyl)-4-mercapto-pyrrolidine-1-carboxylic acid 4-nitro-benzyl ester

(2S,4R)-4-Acetylsulfanyl-2-((3S,4S)-3,4-dihydroxy-pyrrolidine-1-carbonyl)-pyrrolidine-1-carboxylic acid 4-nitro-benzyl ester

(4R,5S,6S)-3-[(3R,5S)-5-((3R,4R)-3,4-Dihydroxy-pyrrolidine-1-carbonyl)-1-(4-nitro-benzyloxycarbonyl)-pyrrolidin-3-ylsulfanyl]-6-((R)-1-hydroxy-ethyl)-4-methyl-7-oxo-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid 4-nitro-benzyl ester

(4R,5S,6S)-3-[(3R,5S)-5-((3S,4S)-3,4-Dihydroxy-pyrrolidine-1-carbonyl)-1-(4-nitro-benzyloxycarbonyl)-pyrrolidin-3-ylsulfanyl]-6-((R)-1-hydroxy-ethyl)-4-methyl-7-oxo-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid 4-nitro-benzyl ester

(2S,4R)-4-Acetylsulfanyl-2-((3R,4R)-3,4-dihydroxy-pyrrolidine-1-carbonyl)-pyrrolidine-1-carboxylic acid 4-nitro-benzyl ester

(2S,4R)-4-Acetylsulfanyl-pyrrolidine-1,2-dicarboxylic acid 1-(4-nitro-benzyl) ester