Determination of tautomeric preference of fenobam in solution by high-resolution NMR spectroscopy

In this work, tautomeric preference of fenobam in solution was investigated by homonuclear and heteronuclear solution nuclear magnetic resonance (NMR) spectroscopy. 1 H– 1 H nuclear Overhauser effect spectroscopy (NOESY) spectrum revealed that fenobam in liquid state exists exclusively in one of the two possible tautomeric structures, which was confirmed by 1 H– 13 C HSQC and heteronuclear multiple bond correlation (HMBC) spectra. Moreover, difference between the two tautomeric structures was studied by theoretical calculations, which further proved the result obtained by the NMR experiments.