(2S,4R)-2-formyl-4-tert-butyldimethylsilyloxy-1-(4-nitrobenzyloxycarbonyl)pyrrolidine

(2S,4S)-2-((S)-4-Carbamoyl-[1,3]thiazinan-2-yl)-4-mercapto-pyrrolidine-1-carboxylic acid 4-nitro-benzyl ester

(S)-2-[(2S,4S)-4-Mercapto-1-(4-nitro-benzyloxycarbonyl)-pyrrolidin-2-yl]-[1,3]thiazinane-4-carboxylic acid ethyl ester

(4R,2S)-4-(tert-butyldimethylsilanyloxy)-2-[3-(2-thiomorpholin-4-yl-ethanesulfonyl)thiazolidin-2-yl]-1-(p-nitrobenzyloxycarbonyl)pyrrolidine

(2S,4S)-4-Mercapto-2-[3-(2-thiomorpholin-4-yl-ethanesulfonyl)-thiazolidin-2-yl]-pyrrolidine-1-carboxylic acid 4-nitro-benzyl ester

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

(4R,5S,6S)-6-((R)-1-Hydroxy-ethyl)-3-[(3S,5S)-5-(3-methanesulfonyl-thiazolidin-2-yl)-1-(4-nitro-benzyloxycarbonyl)-pyrrolidin-3-ylsulfanyl]-4-methyl-7-oxo-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid 4-nitro-benzyl ester

(4R,5S,6S)-6-((R)-1-Hydroxy-ethyl)-3-[(3S,5S)-5-(3-isopropyl-thiazolidin-2-yl)-1-(4-nitro-benzyloxycarbonyl)-pyrrolidin-3-ylsulfanyl]-4-methyl-7-oxo-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid 4-nitro-benzyl ester

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

6-(1-hydroxy-ethyl)-4-methyl-3-(1-(4-nitro-benzyloxycarbonyl)-5-{3-[2-(4-pyrimidin-2-yl-piperazin-1-yl)-ethanesulfonyl]-thiazolidin-2-yl}-pyrrolidin-3-ylsulfanyl)-7-oxo-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid 4-nitro-benzyl ester

(2S,4R)-2-[3-(2-chloroethanesulfonyl)thiazolidin-2-yl]-4-(tert-butyldimethylsilanyloxy)-1-(p-nitrobenzyloxycarbonyl)pyrrolidine

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

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

2-[(4R,2S)-4-(tert-butyldimethylsilanyloxy)-1-(p-nitrobenzyloxycarbonyl)pyrrolidin-2-yl]-[1,3]thiazinane-4(R)-carboxylic acid

(2S,4R)-4-(tert-Butyl-dimethyl-silanyloxy)-2-{3-[2-(4-pyrimidin-2-yl-piperazin-1-yl)-ethanesulfonyl]-thiazolidin-2-yl}-pyrrolidine-1-carboxylic acid 4-nitro-benzyl ester

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

2-[(4R,2S)-4-(tert-butyldimethylsilanyloxy)-1-(p-nitrobenzyloxycarbonyl)pyrrolidin-2-yl]-[1,3]thiazinane-4(R)-carboxylic acid ethyl ester

(4R,2S)-4-(tert-butyldimethylsilanyloxy)-2-(3-methylthiazolidin-2-yl)-1-(p-nitrobenzyloxycarbonyl)pyrrolidine

(4R,2S)-4-(tert-butyldimethylsilanyloxy)-2-[((R)-4-carbamoyl)thiazolidin-2-yl]-1-(p-nitrobenzyloxycarbonyl)pyrrolidine