Configurational assignments of the diastereomers of 3,3′‐(1,2‐ethanediyl)bis[2‐(3‐fluorophenyl)‐5‐methyl‐4‐thiazolidinone] derivative with four stereogenic centers

Diastereomers of antiinflammatory/analgesic and antihistaminic 3,3′[(1,2‐ethanediyl)bis(2‐aryl‐4‐thiazo‐lidinone)] derivatives possessing two stereogenic centers (indicated as BIS 2*C) have been widely investigated in recent years. The 5,5′‐dimethyl analogues (BIS 4*C), now reported, have been synthesized by reaction of (±) α‐mercaptopropionic acid and N,N'‐di(3‐fluorobenzyliden)ethylenediamine. Because the 2 and 2′carbons bear the same groups and similarly the 5 and 5′ carbons, and the latter groups are different from the former, four enantiomeric pairs and two meso forms exist in this situation. These diastereomers were identified by the concerted use of nmr spectroscopy and hplc on chiral stationary phase.