Comparison of resolution methods for racemic 8-(phenylsulfinyl)-1-naphthoic acid

Despite of the fact that resolution is an extremely important process in the pharmaceutical and agrochemical industries, the development of the separation of enantiomers is still based on trial-and-error experiments. In order to compare the different procedures, the resolution of 8-(phenylsulfinyl)-1-naphthoic acid 1 was carried out by chiral organic bases using heat facilitated diastereomeric crystallization, enantioselective liquid–liquid extraction and chiroselective transport. The results give valuable information about the interactions in the racemate/resolving agent/solvent system, which helps with the understanding and development of resolution processes. Diastereomeric crystallization with brucine as a resolving agent afforded enantiomerically pure (?)-1.