2-iminothiazoline-4-carboxylic acid (ITCA), protein adducts,
Only its Enol tautomer
qualifies it to be a UVA filter with a [lambda]max of 357nm.
The minimized internal energies (total energy and binding energy) beside the formation energy (Tables 1 and 2) of 21 tautomers
suggest their high stability which outweigh their production from the coupling reaction and indicate that the most stable tautomer
Dziembowska et al., "Keto-enol tautomerism of two structurally related Schiff bases: Direct and indirect way of creation of the excited keto tautomer
," Chemical Physics Letters, vol.
As a [beta]-diketone, curcumin also exists as a keto-enol tautomer
that chelates transition metal ions with high affinity.
Using Pipeline Pilot of SciTegic to enumerate the tautomer
, stereoisomers and protonation/deprotonation form at pH 7.4 of the active and decoy compounds.
Principle: Creatinine in alkaline medium reacts with picric acid to form a red tautomer
of creatinine picrate, the intensity of which is measured by colorimeter at 520nm.
In deuterated acetone, regioisomer 14aS is mainly present as the thioxo tautomer
II whose proton signals are downfield shifted with respect to tautomer
I in nice keeping with the observations reported in literature for thiopurine derivatives .
The resulting 2-hydroxychromanone then may be in equilibrium with its tautomer
Therefore, we considered the additional two models of the dissociated (Figure 3(b), Scheme 2) and tautomer
(Figure 3(c), Scheme 2) states and calculated the frequencies of these two models which are shown in Tables 3 and 4.
However, the predominant keto-enol tautomer
in aprotic/apolar solvent exhibited an absorption peak at 420 nm .
[sup.1]H-NMR Spectra: In the [sup.1]H-NMR spectra of triazolothiadiazines (III), the characteristic downfield signal at [delta] 8.70 ppm attributed to the -N=C-SH (-NH-C=S of the tautomer
) in compound II is present, as is a sharp signal at [delta] 7.32 ppm attributable to the N-N[H.sub.2] group in the parent triazole .