NMR SPECTROSCOPIC AND THEORETICAL STRUCTURAL-ANALYSIS OF 5,5-DISUBSTITUTED HYDANTOINS IN SOLUTION

The H-1, C-13 and (partly) the N-15 NMR spectra of a number of 5,5-dis ubstituted hydantoins were recorded and assigned by the various method s of 1D and 2D NMR spectroscopy. Employing the NMR parameters, thus ob tained, the NOEs between the different protons within the molecules an d the results of accompanying semiempirical (AM1 and PM3, respectively ) and ab initio (3-21G and, when sulfur atom is present, 3-21G) quant um chemical calculations the tautomerism, the acidity, the stereochemi stry and the pi-electron density distribution along the hydantoin mole cule was studied.