(4R,5S,6S)-3-[(3S,5S)-1-Allyloxycarbonyl-5-(4-methyl-4H-[1,2,4]triazol-3-ylsulfanylmethyl)-pyrrolidin-3-ylsulfanyl]-6-((R)-1-hydroxy-ethyl)-4-methyl-7-oxo-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid allyl ester

(2S,4S)-4-Mercapto-2-([1,2,3]thiadiazol-5-ylsulfanylmethyl)-pyrrolidine-1-carboxylic acid allyl ester

(2S,4S)-4-Mercapto-2-(4-methyl-pyrimidin-2-ylsulfanylmethyl)-pyrrolidine-1-carboxylic acid allyl ester

(4R,5S,6S)-3-[(3S,5S)-1-Allyloxycarbonyl-5-(3-methylcarbamoyl-pyridin-2-ylsulfanylmethyl)-pyrrolidin-3-ylsulfanyl]-6-((R)-1-hydroxy-ethyl)-4-methyl-7-oxo-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid allyl ester

(2S,4S)-4-Mercapto-2-(1-methyl-1H-tetrazol-5-ylsulfanylmethyl)-pyrrolidine-1-carboxylic acid allyl ester