Mass spectral and theoretical studies on the tautomerism of selected thioesters

Among carbonyl compounds esters are not usually involved in tautomeric equilibrium with the exception of β-ketoesters and thioesters.We show that mass spectrometry data are helpful in demonstrating the occurrence of the enol structure for thioesters, particularly significant for the dithio analogues.AM1 semiempirical MO calculations are also consistent with the experimental results.