1-Hydroxy-pentan-2-on, 1-hydroxy-pentan-2-one, Hydroxymethyl-propyl-keton, 1-Hydroxy-2-pentanone, 2-Pentanone,1-hydroxy; l-hydroxy-2-oxopentane; L-hydroxyproline methyl ester hydrochloride; 4S-hydroxy-1-pyrrolidine-2R-carboxylic acid methyl ester hydrochloride salt; 1-hydroxy-2-oxopentane;, methyl (2R,4S)-4-hydroxypyrrolidine-2-carboxylate hydrochloride