Study on enol – enol tautomerism of 5-(4-chlorophenyl)-1-phenyl-4-acetyl-3-hydroxy -3-pyrrolin-2-one based on NMR spectroscopy recorded in DMSO-d6

Tautomerism is a special chemical phenomenon that involves the migration of a proton between two tautomeric structures. Moreover, this dynamic equilibrium also plays a crucial role in modern medicinal chemistry due to its existence in the mechanism of many drugs’ actions. This study has explored the enol – enol tautomerization of 5-(4-chlorophenyl)-1-phenyl-4-acetyl-3-hydroxy-3-pyrrolin-2-one in deuterated dimethyl sulfoxide via NMR measurement. The recorded spectra have shown that there was a fast chemical equilibrium process in NMR time-scale between two enolic structures which resulted in the broadening of 13C resonance signals. More importantly, the spin – spin coupling between hydrogens and carbons has been recorded via 2D HSQC and HMBC spectra in which the resonance signals of all individual atoms have been recognized.