A Preliminary Study on Predicting the 13c Chemical Shifts for a Series of Disubstituted 2,3-Diphenyl-1,3-Thiazolidin-4-Ones

Abstract

A successful attempt has been made to predict l3 C chemical shifts for a series of disubstituted 2,3-diphenyl-l,3-thiazolidin-4-ones. Prior work has shown that substituents placed on either phenyl ring of the 2,3-diphenyl-l,3-thiazolidin-4-one system affect the electron density surrounding the C-2, C-4 and C-5 atoms. These changes are reflected iη the different nmr chemical shifts for these carbon atoms relative to the unsubstituted compound. The l3 C chemical shifts for the C-2, C-4 and C-5 carbons of these compounds have previously been shown to correlate with Hammett σ constants and Swain Lupton dual substituent parameters. Because of these correlations we decided to investigate the potential for predicting l3 C chemical shifts for C-2, C4 and C-5 in the thiazolidinone ring based on the known shifts for the two monosubstituted series of compounds. The effect of the substituents on the l3 C chemical shifts for the C-2, C-4 and C-5 carbons in the disubstituted 2,3-diphenylthiazolidinones are discussed relative to the two mono-substituted 2,3-diphenylthiazolidinone series. The data is then used to predict the 13 C chemical shift values at C-2, C-4 and C-5 in the thiazolidinone ring with all possible substituents combinations in the 2-phenyl and 3-phenyl rings.

Verifying the Predictability of 13C Chemical Shifts for a Series of Substituted-2-(4-Chlorophenyl)-3-Phenyl-1,3-Thiazolidin-4-Ones

“…The results shown in Table 2 show a significant additive effect with respect the sensitivity to the chemical shift values at the C-2 carbon when both rings are substituted with the same substituents at the same sites in both ring (either both para or both meta). This is manifested by an absolute  value of 2.16 (Tierney et al, 2005). In the cases where there is only one substituent in one ring (Series 1 and 2), these exhibit the next highest sensitivity to substituent changes with www.ccsenet.org/ijc…”

“…The equation used to predict the chemical shift () values for the bis-disubstituted series is shown by Equation 2. A reasonably good correlation was determined to exist between experimental and predicted values for the 13 C chemical shifts when applying Equation 2 relating the chemical shift values for the two monosubstituted series (Series 1 and 2) to the disubstituted series (Series 3) (Tierney et al, 2005). The substituents used for all compounds in Series 1-3 that have been used to develop the relationship, represented by Equation 2, are shown in Figure 1.…”

“…(m/z) 323, (M + , found 100%, calc. 100%) C 15 H 11 Cl 2 NOS (323.90) (Tierney, 2005). 138.58,137.65,135.01,134.81,130.01,129.29,128.25,127.26,125.53,123.35 (Ar) 138.71,137.63,135.03,130.27,130.18,129.28,128.41,128.27,123.89,122.61 (Ar) (Tierney, 1996a).…”

“…The two monosubstituted chemical shift values were then used to predict the 13 C chemical shift values at the C-2, C-4 and C-5 sites values for a bis-(disubstituted) -2,3-diphenyl-1,3-thiazolidin-4-one series; where both substituents are the same and at the same location on both phenyl rings. The bis-(disubstituted) -2,3-diphenyl-1,3-thiazolidin-4-one series was also synthesized in order to compare observations to predicted values (Tierney et al, 2005). Correlations relating electronic effects from substituents in the phenyl rings to the observed chemical shifts for the monosubstituted and bis-disubstituted series utilized a form of the Hammett Equation, shown by Equation 1.…”

Selective Synthesis of Substituted 3-Aryl-2-phenyl-1,3-thiazolidin-4-one Sulfoxides and Sulfones by S-Oxidation with Oxone

“…The meta-and para-substituted 3-aryl-2-phenyl-1,3-thiazolidin-4-ones 1c-o used in this evaluation had been previously prepared by sequential condensation reactions. (Tierney et al, 2005) The meta-and para-CF 3 -substituted compounds, 1a and 1b, were likewise prepared by condensation of benzaldehyde with the respective substituted aniline to produce an imine intermediate, followed by condensation with thioglycolic acid. (Scheme 2) Reaction progress in both steps was monitored by the collection of water in a Dean-Stark trap.…”