4-benzylsulfanyl-2-[(4-methoxy-benzenesulfonyl)-(2-morpholin-4-yl-2-oxo-ethyl)-amino]-N-trityloxy-butyramide

4-benzylsulfanyl-2-{(4-methoxy-benzenesulfonyl)-[(2,4,6-trimethoxy-benzylcarbamoyl)-methyl]-amino}-butyric acid

4-benzylsulfanyl-2-[cyclohexylcarbamoylmethyl-(4-methoxy-benzenesulfonyl)-amino]-butyric acid

4-benzylsulfanyl-2-[[(cyclohexylmethyl-carbamoyl)-methyl]-(4-methoxy-benzenesulfonyl)-amino]-butyric acid

4-benzylsulfanyl-2-[[(dicyclohexylmethyl-carbamoyl)-methyl]-(4-methoxy-benzenesulfonyl)-amino]-butyric acid methyl ester