Article

Abstract

Sterically hindered N-(o-aryl)-rhodanines (a) (N-(o-aryl)-2-thioxo-4-thiazolidinones) have been synthesized and the N-(o-tolyl) and N-(o-chlorophenyl) derivatives have been converted to their dioxo analogs (b) (N-(o-aryl)-2,4-thiazolidine- diones). The chirality of the compounds in their conformational ground states was proved by detection of the diastereotopic protons or methyl groups at C-5 of the heteroring using 1H and 13C NMR spectroscopy. In the presence of the optically active auxiliary (S)-(+)-1-(9-anthryl)-2,2,2-trifluoroethanol the enantiomers of the racemic mixtures formed diastereomeric association complexes via H-bonding.Key words: chirality, chiral auxiliary, rotational isomerism, N-(o-aryl)-rhodanines, N-(o-aryl)-2,4-thiazolidinediones, 1H and 13C NMR.