(2S,4S)-4-Acetylsulfanyl-2-[(E)-2-(3-chloro-isoxazol-5-yl)-vinyl]-pyrrolidine-1-carboxylic acid allyl ester

(2S,4S)-2-[(E)-2-(3-Chloro-isoxazol-5-yl)-vinyl]-4-mercapto-pyrrolidine-1-carboxylic acid allyl ester

(4R,5S,6S)-3-{(3S,5S)-1-Allyloxycarbonyl-5-[(E)-2-(3-chloro-isoxazol-5-yl)-vinyl]-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