Synonyms: L-Proline,4-hydroxy-, ethyl ester, hydrochloride, (4R)- (9CI); L-Proline, 4-hydroxy-,ethyl ester, hydrochloride, trans-; Proline, 4-hydroxy-, ethyl ester,hydrochloride, L- (6CI,8CI); (2S,4R)-4-Hydroxypyrrolidine-2-carboxylic acidethyl ester hydrochloride; 4-Hydroxy-L-proline ethyl ester hydrochloride; Hydroxyprolineethyl ester hydrochloride; L-Hydroxyproline ethyl ester hydrochloride