Disclosed is a method for preparing (+)-(2S,3S)-2-(3-chlorophenyl)-3,5,5-trimethyl-2-morpholinol, pharmaceutically acceptable salts, and pharmaceutically acceptable solvates thereof, such as the (+)-(2S,3S)-2-(3-chlorophenyl)-3,5,5-trimethyl-2-morpholinol hydrochloride salt via dynamic kinetic resolutions.