(2R,4S)-2-{2-[(Z)-Hydroxyimino]-2-[(piperazine-1-carbonyl)-amino]-ethyl}-4-tritylsulfanyl-pyrrolidine-1-carboxylic acid allyl ester

(2R,4S)-2-(5-Carbamoyl-[1,2,4]oxadiazol-3-ylmethyl)-4-mercapto-pyrrolidine-1-carboxylic acid allyl ester

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

(2S,4S)-2-{[(4-Hydroxy-piperidine-1-carbonyl)-amino]-methyl}-4-tritylsulfanyl-pyrrolidine-1-carboxylic acid allyl ester

(2S,4S)-2-{[(Piperazine-1-carbothioyl)-amino]-methyl}-4-tritylsulfanyl-pyrrolidine-1-carboxylic acid allyl ester