Potential Antiinflammatory Agents. II. Synthesis and Structure-Activity Relationships of 6-Chloro-5-cyclohexylindan-1-carboxylic Acid (TAI-284) and Related 5-Substituted Indan-1-carboxylic Acids

6-Chloro-5-cyclohexylindan-1-carboxylic acid (TAI-284) and related 5-substituted indan-1-carboxylic acids were prepared for the evaluation of antiinflammatory action. Among them, TAI-284 showed the most potent activity, comparable to that of indomethacin. The replacement of the cyclohexyl moiety at C-5 by other alkyl groups such as isobutyl or isopropyl, or the removal of the chlorine atom at C-6 resulted in a considerable reduction of the activities. The resolution of TAI-284 was effected with quinine, and it was found that the antiinflammatory activity virtually resided in the dextro isomer, the absolute configuration of which was assigned the sinister series by the optical rotatory dispersion spectrum and X-ray crystarography.