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

Lee J. Silverberg, Emily R. Bear, Kristin N. Foose, Kory A. Kirkland, Rachel R. McElvaney, Kevin Cannon, John Tierney, Samuel Lascio, Kirubel Mesfin, Daniel Mitchell, Sarah Sharkey, Lexy So, Jason Treichel, Matthew Waxman, Anthony Lagalante


Previously, an “additivity” equation relating experimental 13C chemical shift data for two monosubstituted diphenyl-1,3-thiazolidin-4-one series was developed to predict chemical shifts for a similarly substituted bis-disubstituted thiazolidinone series. The sites of interest in the 1,3-thiazolidin-4-one are at the C-2, C-4, and C-5 carbons. The empirically derived equation for predicting the chemical shifts is dXY = dH + (dX-dH) + (dY-dH) where dXY is the predicted chemical shift for the disubstituted thiazolidinone: dH is the experimental chemical shift for the unsubstituted thiazolidinone, dX is the experimental chemical shift for substituent in the 2-phenyl ring, and dY is the experimental chemical shift for substituent in the N-(3)-phenyl ring. This article discusses the application of the aforementioned equation with respect to a new series of 2-(p-chlorophenyl)-phenyl-substituted-3-phenyl-1,3-thiazolidin-4-oneswith a comparison of both experimental and predicted 13C chemical shifts for the C-2, C4 and C-5 sites in the thaizolidinone ring. Utilization of the equation showed a level of chemical shift predictability with a degree of accuracy in concert with a previously reported series. The degree of predictability again showed a dependency on the particular substituent and the chemical shift for the site being predicted. This was ±0.06 ppm for C-2, ±0.2 ppm for C-4 and ±0.09 ppm for C5. Finally, there was a correlation between Hammett s values and the substituent chemical shifts using 13C values at C-2. The r value was -0.86 indicating that the C-2 carbon preferred a positive charge.

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International Journal of Chemistry   ISSN 1916-9698 (Print)   ISSN 1916-9701 (Online)

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