Photoisomerization of the enol form of 1,3-dicarbonyl compounds

1977 ◽  
Vol 99 (8) ◽  
pp. 2723-2729 ◽  
Author(s):  
D. Veierov ◽  
T. Bercovici ◽  
E. Fischer ◽  
Y. Mazur ◽  
A. Yogev
Keyword(s):  
Enol Form ◽  
Dicarbonyl Compounds

ChemInform Abstract: PHOTOISOMERIZATION OF THE ENOL FORM OF 1,3-DICARBONYL COMPOUNDS

1977 ◽  
Vol 8 (27) ◽  
pp. no-no
Author(s):  
D. VEIEROV ◽  
T. BERCOVICI ◽  
E. FISCHER ◽  
Y. MAZUR ◽  
A. YOGEV
Keyword(s):  
Enol Form ◽  
Dicarbonyl Compounds

Synthesis and structure of new trichloromethyl-β-diketones — 5-Trichloromethylisoxazole and 5-isoxazolecarboxylic acid derivatives

2005 ◽  
Vol 83 (8) ◽  
pp. 1171-1177 ◽  
Author(s):  
Marcos A.P Martins ◽  
Sergio Brondani ◽  
Victor L Leidens ◽  
Darlene C Flores ◽  
Sidnei Moura ◽  
...  
Keyword(s):  
Hydroxylamine Hydrochloride ◽  
Enol Form ◽  
Improved Method ◽  
Keto Form ◽  
Dicarbonyl Compounds ◽  
Multinuclear Nmr ◽  
Nmr Study

An improved method for the synthesis of a new series of trichloromethyl-β-diketones including 1,1,1-trichloropentan-2,4-dione (2a), 1,1,1-trichloro-3-methylhexan-2,4-dione (2b), 4,4,4-trichloro-1-phenylbutan-1,3-dione (2c), 4,4,4-trichloro-2-methyl-1-phenylbutan-1,3-dione (2d), 2-trichloroacetylcyclohexanone (2e), 4-tert-butylcyclohexanone (2f), 4-tert-butylcycloheptanone (2g), and 4-tert-butylcyclooctanone (2h) is reported. A multinuclear NMR study showed that β-dicarbonyl compounds 2b and 2d–2h are predominantly in the keto form and 2a and 2c are in the enol form. The trichloromethyl-β-diketones react with hydroxylamine hydrochloride leading to three sets of isoxazole derivatives.Key words: acetals, acylation, trichloromethyl-1,3-diketones, 2-trichloroacetylcycloalkanones, isoxazoles, cyclocondensation.

scholarly journals Nucleophilic dearomatization of 4-aza-6-nitrobenzofuroxan by CH acids in the synthesis of pharmacology-oriented compounds

2017 ◽  
Vol 13 ◽  
pp. 2854-2861 ◽  
Author(s):  
Alexey M Starosotnikov ◽  
Dmitry V Shkaev ◽  
Maxim A Bastrakov ◽  
Ivan V Fedyanin ◽  
Svyatoslav A Shevelev ◽  
...  
Keyword(s):  
Enol Form ◽  
Polar Solvents ◽  
No Donor ◽  
Dicarbonyl Compounds ◽  
Ch Acids ◽  
Electrophilic Character

4-Aza-6-nitrobenzofuroxan (ANBF) reacts with 1,3-dicarbonyl compounds and other CH acids to give carbon-bonded 1,4-adducts – 1,4-dihydropyridines fused with furoxan ring. In the case of most acidic β-diketones, which exist mainly in the enol form in polar solvents, the reactions proceed in the absence of any added base emphasizing the highly electrophilic character of ANBF. The resulting compounds combine in one molecule NO-donor furoxan ring along with a pharmacologically important 1,4-dihydropyridine fragment and therefore can be considered as prospective platforms for the design of pharmacology-oriented heterocyclic systems.

scholarly journals Determination of the enol form of asymmetric 1,3-dicarbonyl compounds: 2D HMBC NMR data and DFT calculations

2018 ◽  
Vol 83 (9) ◽  
pp. 953-968
Author(s):  
Meltem Tan ◽  
İshak Bildirici ◽  
Nurettin Mengeş
Keyword(s):  
Experimental Data ◽  
Driving Force ◽  
Theoretical Calculations ◽  
Enol Form ◽  
Dihedral Angles ◽  
Dicarbonyl Compounds ◽  
1H And 13C Nmr ◽  
Nmr Data ◽  
Cdcl3 Solution

In this study, a series of asymmetric aryl 1,3-dicarbonyl compounds were synthesized and their enol forms were observed via experimental data and theoretical calculations. According to the 1H- and 13C-NMR results, all the investigated compounds were found as a single enol form in CDCl3 solution. Moreover, their HMBC spectra were applied to identify the observed enol forms and correlations between certain protons and carbon atoms were considered. The dihedral angles of the asymmetric compounds that have aryl units on both sides were calculated by DFT to understand the reason for the observed enol forms. Small dihedral angles caused longer conjugation, resulting in more stable compounds and it was found that the observed enol forms were based on small dihedral angles, namely, resonance is the driving force. Furthermore, the compounds possessing both aryl and alkyl moieties prefer the enol form towards the aromatic ring side due to longer conjugation.

Dicarbonyl derived post-translational modifications: chemistry bridging biology and aging-related disease

2020 ◽  
Vol 64 (1) ◽  
pp. 97-110
Author(s):  
Christian Sibbersen ◽  
Mogens Johannsen
Keyword(s):  
Mass Spectrometry ◽  
Future Research ◽  
Amino Acid Residues ◽  
Post Translational Modification ◽  
Dicarbonyl Compounds ◽  
Protein Targets ◽  
Post Translational Modifications ◽  
Reactive Protein ◽  
Glycation End Products ◽  
Direct Mass Spectrometry

Abstract In living systems, nucleophilic amino acid residues are prone to non-enzymatic post-translational modification by electrophiles. α-Dicarbonyl compounds are a special type of electrophiles that can react irreversibly with lysine, arginine, and cysteine residues via complex mechanisms to form post-translational modifications known as advanced glycation end-products (AGEs). Glyoxal, methylglyoxal, and 3-deoxyglucosone are the major endogenous dicarbonyls, with methylglyoxal being the most well-studied. There are several routes that lead to the formation of dicarbonyl compounds, most originating from glucose and glucose metabolism, such as the non-enzymatic decomposition of glycolytic intermediates and fructosyl amines. Although dicarbonyls are removed continuously mainly via the glyoxalase system, several conditions lead to an increase in dicarbonyl concentration and thereby AGE formation. AGEs have been implicated in diabetes and aging-related diseases, and for this reason the elucidation of their structure as well as protein targets is of great interest. Though the dicarbonyls and reactive protein side chains are of relatively simple nature, the structures of the adducts as well as their mechanism of formation are not that trivial. Furthermore, detection of sites of modification can be demanding and current best practices rely on either direct mass spectrometry or various methods of enrichment based on antibodies or click chemistry followed by mass spectrometry. Future research into the structure of these adducts and protein targets of dicarbonyl compounds may improve the understanding of how the mechanisms of diabetes and aging-related physiological damage occur.

Kinetics and mechanism of the reaction of iron(III) with 6-methyl-2,4-heptanedione and 3,5-heptanedione

1990 ◽  
Vol 55 (8) ◽  
pp. 1984-1990 ◽  
Author(s):  
José M. Hernando ◽  
Olimpio Montero ◽  
Carlos Blanco
Keyword(s):  
Aqueous Solution ◽  
Metal Ion ◽  
Activation Parameters ◽  
Enol Form ◽  
Kinetics And Mechanism ◽  
Kinetic Constants ◽  
Steric Factors ◽  
Kinetics Of ◽  
Mechanism Of The Reaction

The kinetics of the reactions of iron(III) with 6-methyl-2,4-heptanedione and 3,5-heptanedione to form the corresponding monocomplexes have been studied spectrophotometrically in the range 5 °C to 16 °C at I 25 mol l-1 in aqueous solution. In the proposed mechanism for the two complexes, the enol form reacts with the metal ion by parallel acid-independent and inverse-acid paths. The kinetic constants for both pathways have been calculated at five temperatures. Activation parameters have also been calculated. The results are consistent with an associative activation for Fe(H2O)63+ and dissociative activation for Fe(H2O)5(OH)2+. The differences in the results for the complexes of heptanediones studied are interpreted in terms of steric factors.

ChemInform Abstract: CONDENSATION OF O-AMINOPHENOL AND α-DICARBONYL COMPOUNDS. PART 1. BENZOXAZINES

1978 ◽  
Vol 9 (18) ◽  
Author(s):  
E. BELGODERE ◽  
R. BOSSIO ◽  
V. PARRINI ◽  
R. PEPINO
Keyword(s):  
Dicarbonyl Compounds

scholarly journals Stereoselective Tandem Iridium-Catalyzed Alkene Isomerization-Cope Rearrangement of ω-diene Epoxides: Efficient Access to Acyclic 1,6-Dicarbonyl Compounds

2021 ◽  
Author(s):  
Rahul Suresh ◽  
Itai Massad ◽  
Ilan Marek
Keyword(s):  
Bond Cleavage ◽  
Cope Rearrangement ◽  
Dicarbonyl Compounds ◽  
Alkene Isomerization ◽  
Efficient Access

The Cope rearrangement of 2,3-divinyloxiranes, a rare example of epoxide C-C bond cleavage, results in 4,5-dihydrooxepines which are amenable to hydrolysis, furnishing 1,6-dicarbonyl compounds containing two contiguous stereocenters at the 3- and 4- positions. We employ...

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