Effects and conformational analysis of some substituted 2,3-diphenyl-1,3-thiazolidin-4-ones

Substituents placed on the phenyl rings of 2,3-diphenyl-1,3-thiazolidin-4-one affect the electron density surrounding both the methine proton and the C(2) carbon. These changes are reflected in the differing chemical shifts for these atoms relative to the parent compound. The other carbons in the heterocyclic ring appear to be similarly affected by substituents on the phenyl rings. Correlations for the effects of various substituents in both the 2-and 3-phenyl rings with the ¹H and ¹³C chemical shifts for the aforementioned sites are discussed using both Hammett and Swain-Lupton dual parameter methods. A conformational analysis using ab initio calculations is in agreement with the observed NMR data.