Optical resolution and absolute configuration of a nonsteroidal antiinflammatory drug, 2-(10,11-dihydro-10-oxodibenzo- [b,f]thiepin-2-yl)propionic acid.

The title compound (+/-)-1 (CN-100) was efficiently resolved into a pair of enantiomers by fractional crystallization of the diastereomeric salts of (-)- and (+)-phenylethylamine. The purity of the enantiomers was determined using the chiral cellulose column (CHIRALCEL OJ) which was allowed direct separation of the enantiomers. A separation factor (alpha) of 1.73 was obtained. X-Ray crystallographic analysis of the (+)-isomer [salt of (-)-1-(4-bromophenyl)ethylamine] showed that this enantiomer has S-configuration. Biological studies have shown that only the (+)-isomer has antiinflammatory activity. Racemizaiton of (-)-isomer was carried out by heating its propionic acid solution in the presence of mineral acid, such as HBr.