The Influence of Chelation on the Stability of Enediols. I. 2-Pyridoin, 1-Phenyl-2-(2-Pyridyl)-1,2-Ethenediol, and 1-Phenyl-2-(4-Pyridyl)-1,2-Ethenediol

Synthesis, characterisation and crystal structure of 1,2-bis(6-methylpyridin-2-yl)ethene-1,2-diol

“…The characteristic IR bands 10,11 for the title compound were: a band at 3449 cm -1 assigned to νO-H weak absorption due to an intramolecular hydrogen bond between O-H⋅⋅⋅⋅N, the low intensity band at 1649 cm -1 was assigned to -C=C-stretching vibration double bond, two absorption peaks at 1590 and 1569 cm -1 assigned to -C=N-and -C=C-of pyridine rings, the band at 1226 cm -1 assigned to νC-O and the absorption peak at 1180 cm -1 to deformation vibration of O-H groups. 1 H NMR spectrum analysis showed a very symmetric molecule with a singlet at 2.5 ppm assigned to three protons of the -CH 3 in the pyridine ring 6-position. The signals for the three protons of the pyridine ring were: a doublet between 7.26 and 7.24 with J= 7.68 Hz, another doublet at 7.62-7.60 with J= 8.08 Hz and multiplet between 8.02-7.87 ppm with J= 8.08, and 7.68 Hz and the signal for the proton O-H was missing.…”

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From the benzoin condensation of pyridine-2-carbaldehyde Buehler et al 1 reported that instead of the expected benzoin (2-hydroxy[1,2-di(pyridin-2-yl)]ethane-1-one), 1,2-di(pyridin-2-yl)ethene-1,2-diol was produced. The authors proposed that chelation (one type of hydrogen bond) is an important factor in increasing the stability of the three enediols studied, (Fig.

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One‐Pot Synthesis of Unsymmetrical Benzils by Oxidative Coupling Using Selenium Dioxide and p‐Toluenesulfonic Acid Monohydrate

“…[1,2] Some benzils exhibit the potential for biological activities, which includes the inhibition of mammalian carboxylesterases. [3] A number of synthetic pathways for the preparation of aryl/heteroaryl 1,2-diketones involve the oxidation of precursors such as olefins with selenium dioxide [4,5] or potassium permanganate, [6,7] methylene ketones by selenium dioxide, [8,9] bismuth nitrate-copper(II) acetate, [10] or oxygen in the presence of Fe III -ethylenediaminetetraacetic acid. [11] Recently, we conducted a literature survey of the synthetic utility of SeO 2 oxidation processes in synthetic chemistry, in particular, the use of SeO 2 in the presence of acids to promote new C-C bond formation to synthesize unsymmetrical benzils.…”

HPLC Determination of Guanidino Compounds in Serum of Uremic Patients Using Pyridoin as Derivatizing Reagent

“…Further solutions were prepared by appropriate dilutions. The derivatizing reagent pyridoin was prepared as reported [28] from 2-pyridinecarboxaldehyde, following benzoin type condensation in pyridine-water (30:70 v=v) as the solvent. The derivatizing reagent pyridoin solution (4 mmol) was prepared in formamide-methanol; whereas, pyridoin (85 mg) was dissolved in 20 ml of formamide and the volume adjusted to 100 mL with methanol.…”