These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Keto-enol tautomerism in crystals of 3-[hydroxy(phenyl)methyl]-2,5,7-trimethyl-2,3-dihydropyrido[3,2-e][1,2]thiazin-4-one 1,1-dioxide and 3-(1-hydroxyethylidene)-2,5,7-trimethyl-2,3-dihydropyrido[3,2-e][1,2]thiazin-4-one 1,1-dioxide.
    Author: Karczmarzyk Z.
    Journal: Acta Crystallogr C; 2008 Nov; 64(Pt 11):o590-4. PubMed ID: 18989086.
    Abstract:
    In the crystal structures of the title compounds, C(17)H(16)N(2)O(4)S, (I), and C(12)H(14)N(2)O(4)S, (II), the co-existence of both possible keto/enol (4-keto and 4-hydroxy) tautomers, with visible predominance of the 4-keto form, is observed. The tautomeric equilibrium is stabilized by strong intramolecular O-H...O hydrogen bonding. The (13)C NMR spectra recorded for (I) and (II), and theoretical calculations at the RHF SCF ab initio 6-31G** level, show the same tautomeric equilibrium in solution and the gaseous phase. The partially saturated thiazine rings in the pyrido[3,2-e][1,2]thiazine rings systems of (I) and (II) adopt a diplanar conformation. The molecular packing in (I) is influenced by weak intermolecular C-H...O hydrogen bonding and C-H...pi interactions. In the crystal structure of (II), the molecules are linked by a combination of O-H...O hydrogen bonding and C-H...pi and pi-pi interactions.
    [Abstract] [Full Text] [Related] [New Search]