(2S,4S)-4-Mercapto-2-(2-piperazin-1-yl-ethylcarbamoyl)-pyrrolidine-1-carboxylic acid allyl ester

(2S,4S)-2-{3-[(Z)-Hydroxyimino]-pyrrolidine-1-carbonyl}-4-mercapto-pyrrolidine-1-carboxylic acid allyl ester

(2S,4S)-4-Mercapto-2-[2-(3-methyl-thioureido)-ethylcarbamoyl]-pyrrolidine-1-carboxylic acid allyl ester

(2S,4S)-2-(2-Methanesulfonylamino-ethylcarbamoyl)-4-tritylsulfanyl-pyrrolidine-1-carboxylic acid allyl ester

(2S,4S)-2-[1-(methoxyimino)-2-(carbamoyaminol)ethyl]-4-tritylthio-1-(allyloxycarbonyl)pyrrolidine