(2S,4R)-1-[(tert-butoxy)carbonyl]-4-hydroxypyrrolidine-2-carboxylic acid

(2S,4R)-1-[(tert-butoxy)carbonyl]-4-isocyano-2-(methoxycarbonyl)pyrrolidine

(2S,4R)-1-[(tert-butoxy)carbonyl]-4-methanesulfonylpyrrolidine-2-carboxylic acid

(2S,4R)-1-[(tert-butoxy)carbonyl]-4-methoxypyrrolidine-2-carboxylic acid

(2S,4R)-1-[(tert-butoxy)carbonyl]-4-methylpyrrolidine-2-carboxylic acid

(2S,4R)-1-{[(9H-fluoren-9-yl)methoxy]carbonyl}-4-(2-methoxy-2-oxoethyl)pyrrolidine-2-carboxylic acid

(2S,4R)-1-{[(9H-fluoren-9-yl)methoxy]carbonyl}-4-(methylsulfanyl)pyrrolidine-2-carboxylic acid

(2S,4R)-1-{[(9H-fluoren-9-yl)methoxy]carbonyl}-4-fluoropyrrolidine-2-carboxylic acid

(2S,4R)-1-{[(9H-fluoren-9-yl)methoxy]carbonyl}-4-hydroxypyrrolidine-2-carboxylic acid

(2S,4R)-1-{[(9H-fluoren-9-yl)methoxy]carbonyl}-4-methanesulfonylpyrrolidine-2-carboxylic acid

(2S,4R)-1-{[(9H-fluoren-9-yl)methoxy]carbonyl}-4-methylpyrrolidine-2-carboxylic acid

(2S,4R)-2,5-bis({[(tert-butoxy)carbonyl]amino})-4-fluoropentanoic acid

(2S,4R)-2,5-diamino-4-fluoropentanoic acid dihydrochloride

(2S,4R)-2-(chloromethyl)-4-methoxypyrrolidine hydrochloride

(2S,4R)-2-(trifluoromethyl)-1,3-thiazolidine-4-carboxylic acid

(2S,4R)-2-({[(9H-fluoren-9-yl)methoxy]carbonyl}amino)-4-fluoropentanedioic acid

(2S,4R)-2-amino-4-carbamoyl-4-fluorobutanoic acid hydrochloride

(2S,4R)-2-amino-4-fluoro-5-methoxy-5-oxopentanoic acid hydrochloride

(2S,4R)-2-amino-4-fluoropentanediamide hydrochloride

(2S,4R)-2-amino-4-fluoropentanediamide; trifluoroacetic acid

(2S,4R)-2-amino-4-fluoropentanedioic acid hydrochloride

(2S,4R)-2-amino-5,5,5-trifluoro-4-methylpentanoic acid

(2S,4R)-2-amino-5-azido-4-fluoropentanoic acid hydrochloride

(2S,4R)-2-amino-5-carbamimidamido-4-fluoropentanoic acid dihydrochloride

(2s,4r)-2-fluoro-5-azaspiro[3.5]nonane hydrochloride

(2S,4R)-2-methyl-3,4-dihydro-2H-1-benzopyran-4-ol

(2S,4R)-2-pentyl-3,4-dihydro-2H-1-benzopyran-4-ol

(2S,4R)-2-propyl-3,4-dihydro-2H-1-benzopyran-4-ol

(2S,4R)-2-{[(tert-butoxy)carbonyl]amino}-4-carbamoyl-4-fluorobutanoic acid

(2S,4R)-2-{[(tert-butoxy)carbonyl]amino}-4-fluoropentanedioic acid

(2S,4R)-4-(1H-1,2,3-triazol-1-yl)pyrrolidine-2-carboxylic acid dihydrochloride

(2S,4R)-4-(2-methoxy-2-oxoethyl)pyrrolidine-2-carboxylic acid hydrochloride

(2S,4R)-4-(difluoromethoxy)-1-{[(9H-fluoren-9-yl)methoxy]carbonyl}pyrrolidine-2-carboxylic acid

(2S,4R)-4-(tert-butoxy)-1-methylpyrrolidine-2-carboxylic acid

(2S,4R)-4-(tert-butoxy)-1-[(tert-butoxy)carbonyl]pyrrolidine-2-carboxylic acid

(2S,4R)-4-(tert-butoxy)pyrrolidine-2-carboxylic acid

(2S,4R)-4-(trifluoromethoxy)pyrrolidine-2-carboxylic acid hydrochloride

(2S,4R)-4-amino-1-[(tert-butoxy)carbonyl]pyrrolidine-2-carboxylic acid

(2S,4R)-4-aminopentan-2-ol hydrochloride

(2S,4R)-4-aminopyrrolidine-2-carboxylic acid dihydrochloride

(2S,4R)-4-azido-1-[(tert-butoxy)carbonyl]pyrrolidine-2-carboxylic acid

(2S,4R)-4-azido-1-{[(9H-fluoren-9-yl)methoxy]carbonyl}pyrrolidine-2-carboxylic acid

(2S,4R)-4-carbamoyl-2-({[(9H-fluoren-9-yl)methoxy]carbonyl}amino)-4-fluorobutanoic acid

(2S,4R)-4-chloro-1-{[(9H-fluoren-9-yl)methoxy]carbonyl}pyrrolidine-2-carboxylic acid

(2S,4R)-4-chloropyrrolidine-2-carboxylic acid hydrochloride