Theoretical Investigation of Tautomerism Stability of Hydantoin in the Gas Phase and in the Solution

Abstract

Intramolecular 1,3-proton transfer of the keto-enol reactions of heterocyclic systems with several basic centers, O, N, S and Se atoms, are of great interest to medicinal and biochemical applications. Also, understanding of the relative stabilities of heterocyclic tautomers and any subsequent conversions between tautomeric forms is very vital for both structural chemists and biologists 1,2 . Along this line, relative stabilities of various tautomeric structures of five-, six-and sevenmembered ring (dioxo, oxo/thio, oxo/seleno, dithio and diseleno combinations) were investigated using both theoretical and experimental tools [3][4][5][6][7][8][9][10][11][12] ABSTRACTThe relative stability of the different tautomers of hydantoin has been studied through the use of DFT method. The structures and the vibrational frequencies of all stable tautomers and all the transitions states connecting between them have been calculated at the B3LYP/6-311+G(d,p) level of theory in the gas phase and selected solvents using IE-PCM model. Final energies have been obtained in single-point B3LYP/6-311++(3df,2p) calculations. The results show that the diketo tautomer T1 is more stable than the other tautomers. Variation of charge densities at bond critical points, dipole moments and NBO charges on atoms in the solvents were studied.

Hydantoanabaenopeptins from Lake Kinneret Microcystis Bloom, Isolation, and Structure Elucidation of the Possible Intermediates in the Anabaenopeptins Biosynthesis

“…Application of Marfey's method [15] coupled with HR ESI LCMS established the absolute configuration of the amino acids as L-NMeAla, L-Hty, L-Phe, L-Val, D-Lys, and 1:1 D,L-Tyr (Figure S11). We suspect that the tyrosine epimerization occurs due to the easy keto/enol tautomerism of the hydantoin moiety during the compound separation [16]. Based on these arguments, structure 1 was proposed for hydantoanabaenopeptin A.…”

Synthesis, spectroscopy, and theoretical calculations of some 2-thiohydantoin derivatives as possible new fungicides

“…B3LYP is still the most popular DFT method, with plenty of applications. Among others, this functional has been used recently (with almost the same as employed in this study 6-311+G** basis set) to study the tautomerism of the rhodanine molecule [28]. The structural optimisations were followed by the frequency calculations in order to confirm the minimum nature of the calculated geometries.…”