(R)-Pyrrolidine-1,2-dicarboxylic acid 1-(4-nitro-benzyl) ester

<(R)-N-p-nitrobenzyloxycarbonylpyrrolidin-2-yl>carbothioic S-acid

p-nitrobenzyl (5R,6S)-6-<(1R)-hydroxyethyl>-2-<(2R)-N-p-nitrobenzyloxycarbonylpyrrolidin-2-yl>methyl-2-penem-3-carboxylate

<(2R)-N-p-nitrobenzyloxycarbonylpyrrolidin-2-yl>thioacetic S-acid

p-nitrobenzyl 2-<(3S,4R)-3-<(1R)-(tert-butyldimethylsiloxy)ethyl>-4-<((2S)-N-p-nitrobenzyloxycarbonylpyrrolidin-2-yl)acetylthio>-2-oxoazetidin-1-yl>-2-triphenylphosphoranylideneacetate

p-nitrobenzyl 2-<(3S,4R)-3-<(1R)-(tert-butyldimethylsiloxy)ethyl>-4-<<(2R)-N-p-nitrobenzyloxycarbonylpyrrolidin-2-yl>carbonylthio>-2-oxoazetidin-1-yl>-2-triphenylphosphoranylideneacetate

(5R,6S)-6-<(1R)-hydroxyethyl>-2-<<(2S)-pyrrolidin-2-yl>-methyl>-2-penem-3-carboxyic acid

p-nitrobenzyl (5R,6S)-6-<(1R)-(tert-butyldimethylsiloxy)ethyl>-2-<(2S)-N-p-nitrobenzyloxycarbonylpyrrolidin-2-yl-methyl>-2-penem-3-carboxylate

(3S,4R)-3-<(1R)-(tert-butyldimethylsiloxy)ethyl>-4-<<(2S)-N-p-nitrobenzyloxycarbonylpyrrolidin-2-yl>acetylthio>azetidin-2-one

p-nitrobenzyl 2-<(3S,4R)-3-<(1R)-(tert-butyldimethylsiloxy)ethyl>-4-<((2R)-N-p-nitrobenzyloxycarbonylpyrrolidin-2-yl)acetylthio>-2-oxoazetidin-1-yl>-2-hydroxyacetate

(5R,6S)-6-<(1R)-hydroxyethyl>-2-<(2R)-pyrrolidin-2-yl>methyl-2-penem-3-carboxylic acid

(R)-2-{(2R,3S)-3-[(R)-1-(tert-Butyl-dimethyl-silanyloxy)-ethyl]-1-[chloro-(4-nitro-benzyloxycarbonyl)-methyl]-4-oxo-azetidin-2-ylsulfanylcarbonylmethyl}-pyrrolidine-1-carboxylic acid 4-nitro-benzyl ester

p-nitrobenzyl (5R,6S)-6-<(1R)-(tert-butyldimethylsiloxy)ethyl>-2-<(2R)-N-p-nitrobenzyloxycarbonylpyrrolidin-2-yl>-2-penem-3-carboxylate

p-nitrobenzyl 2-<(3S,4R)-3-<(1R)-(tert-butyldimethylsiloxy)ethyl>-4-<<(2S)-N-p-nitrobenzyloxycarbonylpyrrolidin-2-yl>carbonylthio>-2-oxoazetidin-1-yl>-2-triphenylphosphoranylideneacetate

p-nitrobenzyl (5R,6S)-6-<(1R)-(tert-butyldimethylsiloxy)ethyl>-2-<(2S)-N-p-nitrobenzyloxycarbonylpyrrolidin-2-yl>-2-penem-3-carboxylate

(S)-2-{(2R,3S)-3-[(R)-1-(tert-Butyl-dimethyl-silanyloxy)-ethyl]-1-[chloro-(4-nitro-benzyloxycarbonyl)-methyl]-4-oxo-azetidin-2-ylsulfanylcarbonyl}-pyrrolidine-1-carboxylic acid 4-nitro-benzyl ester

(5R,6S)-6-<(1R)-hydroxyethyl>-2-<(2S)-pyrrolidin-2-yl>-2-penem-3-carboxylic acid

p-nitrobenzyl 2-<(3S,4R)-3-<(1R)-(tert-butyldimethylsiloxy)ethyl>-4-<<(2S)-N-p-nitrobenzyloxycarbonylpyrrolidin-2-yl>carbonylthio>-2-oxoazetidin-1-yl>-2-hydroxyacetate

(3S,4R)-3-<(1R)-(tert-butyldimethylsiloxy)ethyl>-4-<(2S)-N-p-nitrobenzyloxycarbonylpyrrolidin-2-yl>carbonylthioazetidin-2-one