A study of the tautomerism of β-dicarbonyl compounds with special emphasis on curcuminoids

Electron‐Deficient Aryl β‐Diketones: Synthesis and Novel Tautomeric Preferences

“…[1][2][3][4][5][7][8][9] Prior researchers have probed the keto-enol and enolenol equilibria of various trifluoromethylated and nonfluorinated aryl β-diketones using computational methods and experimentally in non-polar and polar media. [1,2,[5][6][7][8][9] Ab initio calculations confirm a general thermodynamic stability trend: chelated cis-enol A Ͼ chelated cis-enol B Ͼ diketo form in the gas phase as well as in non-polar and polar, protic solvents. [1,2] In general, while solution state NMR spectroscopic studies can easily distinguish between the diketo and enol tautomers of β-diketones, resolution of the enol tautomeric forms has remained contentious.…”

“…[1,2,[5][6][7][8][9] Ab initio calculations confirm a general thermodynamic stability trend: chelated cis-enol A Ͼ chelated cis-enol B Ͼ diketo form in the gas phase as well as in non-polar and polar, protic solvents. [1,2] In general, while solution state NMR spectroscopic studies can easily distinguish between the diketo and enol tautomers of β-diketones, resolution of the enol tautomeric forms has remained contentious. Enol-enol equilibria in aryl trifluoromethyl β-diketones, for example, have been estimated using a combination of NMR chemical jugated with the aryl ring.…”

A theoretical and experimental NMR study of (+)-biotin methyl ester

“…We have been reporting the characterization by NMR of some relevant pharmaceutical and biological compounds, for instance, Omeprazole [1,2] and curcumin [3]. In particular, we have been interested in biotin methyl ester 1 (3aS,4S,6aR)-hexahydro-2-oxo-1H-thieno [3,4-d]imidazole-4-pentanoic acid methyl ester [4][5][6][7][8], a derivative of biotin 2, in molecular recognition studies trying to improve the binding of 2 with synthetic receptors.…”

The behavior of Gliclazide in solution and in the solid state: a case of organic compound presenting a solid‐solution structure

“…We have been systematically reporting the characterization by NMR of relevant pharmaceutical and biological compounds: Omeprazole, [1,2] curcumin, [3] and biotin methyl ester. [4] We wish to describe now our studies of Gliclazide, 3-(7-azabicyclo[3.3.0]oct-7-yl)-1-(4-methylphenyl)sulfonylurea.…”

“…Also, it is known that the barrier is higher in chloroform than in other solvents. [30,32] In the case of Gliclazide, the signals of both invertomers being only slightly broad in CDCl 3 at 213 K and the average signals in DMSOd 6 3 and about 20-40 kJ mol −1 in DMSO-d 6 . [33] In the solid-state, Gliclazide is an example of substitutional solidsolution, i.e.…”