Optical resolution of 6-fluoro-2-methyl-1,2,3,4-tetrahydroquinoline by supercritical fluid extraction.

6-Fluoro-2-methyl-1,2,3,4-tetrahydroquinoline (FTHQ) enantiomers were separated by supercritical fluid extraction using carbon dioxide. Diastereoisomeric salts were formed from the racemic base with less than one equivalent of O,O'-di-(4-toluoyl)-(2R,3R)-tartaric acid (DPTTA). Further purification was achieved by partial salt formation of the enantiomeric mixture with an achiral acid (HCl) followed by the supercritical fluid extraction of the free enantiomers.