1H, 13C and 17O NMR study of substituent effects in 4-substituted phenylthiol esters

The 1H and 13C NMR spectra of 4-substituted phenylthiol acetates, benzoates and cinnamates and the 17O NMR spectra of a few thiol acetates were measured. The 13C chemical shifts of C-1 of the thiol esters when correlated with appropriate substituent-induced chemical shifts (SCS) of monosubstituted benzenes reveal an enhancement of substituent effect at C-1. Several good dual substituent parameter (DSP) correlations of 13C chemical shifts with σ1 and σR parameters were obtained for the carbons para to the substituent and the carbonyl carbons of all the three series of thiol esters display inverse substituent effects, indicating π-polarization of the thiol ester functionality by the dipole of the substituent. © John Wiley & Sons Ltd.