(R)-methyl 3-amino-4-(phenylthio)butanoate, trifluoroacetic acid salt

(R)-methyl 3-(benzyloxycarbonylamino)-4-(phenylthio)butanoate

(R)-methyl 4-(phenylthio)-3-(4-sulfamoyl-2-(trifluoromethylsulfonyl)phenylamino)butanoate