Cyclic Diketones Research Articles

Efficient organocatalyzed solvent-free selective synthesis of conjugated enones

A series of conjugated dienones and enones were synthesized by a reaction of both conjugated and simple aldehydes, respectively, with 1,3-dicarbonyl compounds and aldehydes under solvent-free conditions at room temperature in the presence of 10 mol % of l-proline as catalyst. The selective formation of one isomer was observed exclusively with most of the 1,3-dicarbonyl compounds and aldehydes. The most commonly formed xanthene derivative from the cyclic diketones is inhibited with our protocol, with the exclusive formation of conjugated dienones only.

Investigation of the Products of Interaction of Cyclic Diketones with Nitrogen‐Containing 1,4‐Binucleophiles.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Investigation of the products of interaction of cyclic diketones with nitrogen-containing 1,4-binucleophiles

The interaction of arylbis(5,5-dimethylcyclohexane-1,3-dion-2-yl)methanes with o-phenylenediamine and o-aminophenol leads to the preparation of 3,3-dimethyl-11-aryl-2,3,4,5,10,11-hexahydrobenzo[b,e]-1,4-diazepin-1-ones and 3,3,6,6-tetramethyl-9-aryl-10-(2-hydroxyphenyl)-2,4,5,7,9-decahydroacridine-1,8-diones respectively. A one-pot method is proposed for the synthesis of derivatives of hexahydrodibenzo[b,e]-1,4-diazepin-1-ones. The structure of the first member of this series was confirmed by X-ray diffraction analysis.

The Formal [3+2+1] Cyclisation of Cyclopropylamines with Carboxylic Anhydrides: A Quick Access to Polysubstituted 2,3,3a,4‐Tetrahydro6(5H)‐indolone Ring Systems

AbstractSeveral 2‐azabicyclo[3.1.0]hexanes were synthesised using the intramolecular version of the Kulinkovich−de Meijere cyclopropanation reaction. Upon heating in the presence of a carboxylic anhydride, the cyclopropane rings of these systems open up to afford vinylogous amides. Depending on the reaction conditions used, the monoacylated compounds may be the major products, or subsequent acylation may take place to afford cyclic diketones. The method is flexible, and it is possible to incorporate different acyl groups in a two‐step sequence. The diketones are easily converted into 2,3,3a,4‐tetrahydro‐6(5H)‐indolone derivatives by intramolecular aldolisation. The products, which are highly functionalised alcohols, are obtained as single diastereoisomers. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Preparation of Cyclic 1,3-Diketones and Their Exploitation in the Synthesis of Heterocycles

Owing to their high reactivity and availability 1,3-dicarbonyl compounds occupy an important place in organic synthesis. It is mainly their high reactivity that predetermines them for the synthesis of various types of compounds, particularly heterocycles. Cyclic 1,3-diketones I(n) (where n is the number of ring carbon atoms), which are suitable precursors for preparation of bicyclic or polycyclic condensed heterocycles, respectively, are an important group of 1,3-dicarbonyl compounds. However, at the same time it must be added that in spite of the relatively simple structure of 1,3- cycloalkanediones their syntheses have yet to be satisfactory solved, especially those for medium-sized and large rings. Therefore, currently the chemistry of common cyclic β-diketones, such as 1,3-cyclohexanedione, 5,5-dimethyl-1,3- cyclohexanedione (dimedone), but also that of 1,3-cyclopentanedione remains best known. In the literature one can already find a large scope of heterocycles synthesized on the basis of the above three diketones, and also data about their biological activity. Works dealing with exploitation of other, higher cyclic diketones are scarce. This article is a continuation of two reviews published by Strakov [1,2], and expands them by results published till the end of 2001. Keywords: heterocycles, cyclic 1,3-diketones, 1,3-dicarbonyl compounds, dimedone

Molecular Sieve (MS 4A) Promoted Cyclocondensation of Hindered, Aromatic Nitrile Oxides and Cyclic Diketones under Mild Conditions.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Amine‐Promoted Cyclocondensation of Highly Substituted Aromatic Nitrile Oxides with Diketones.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Amine-promoted cyclocondensation of highly substituted aromatic nitrile oxides with diketones

Base-promoted cyclocondensation of hindered nitrile oxides and cyclic diketones affords highly functionalized, sterically-encumbered isoxazole products in good yield. The mild reaction conditions (NEt 3, EtOH) are tolerant to a wide variety of functionality and permit the preparation of precursors to complex polycycles typically inaccessible via direct, intermolecular carboncarbon bond forming reactions. The ability to effect the cyclocondensation reaction with a catalytic amount of amine points to the intermediacy of an ammonium enolate as a key reactive species. A convenient, single step preparation of crystalline, stable nitrile oxides from the corresponding oximes enhances the advantages of this methodology for the preparation of functionalized polycycles.

Molecular Sieve (MS 4A) Promoted Cyclocondensation of Hindered, Aromatic Nitrile Oxides and Cyclic Diketones under Mild Conditions

Molecular Sieve (MS 4A) Promoted Cyclocondensation of Hindered, Aromatic Nitrile Oxides and Cyclic Diketones under Mild Conditions

ChemInform Abstract: Reactions of 1,2,4‐Triazines with Nucleophiles. Part 6. Use of SnH Methodology for the Direct Introduction of Cyclic Diketone Residue into the 1,2,4‐Triazine Ring.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Intramolecular tandem Michael-type addition/aldol cyclization induced by TiCl(4)-R(4)NX combinations.

[reaction: see text] Treatment of formyl alpha,beta-enones with a TiCl(4)-R(4)NX combination induces an intramolecular aldol cyclization to furnish 2-acyl-3-halocyclohexanol with three controlled consecutive stereogenic centers. The reaction of bis-alpha,beta-enones with the combination provides cyclic diketones with high stereoselectivity via an intramolecular Michael addition reaction.

The strength of a low-barrier hydrogen bond in water

There are large differences between the acidity of the enol of the acyclic diketone, 2,4-pentanedione and those of two cyclic diketones, 1,3-cyclopentanedione and 1,3-cyclohexanedione. Computational studies have demonstrated that these differences are largely due to the strength of the internal low-barrier hydrogen bond (LBHB) in the enol of 2,4-pentanedione. It is thus estimated that the lower limit of the additional free energy of formation in water for this LBHB over that of a conventional hydrogen bond is 4.1–5.3 kcal mol −1.

Reactions of 1,2,4-Triazines with Nucleophiles. 6. Use of SNH Methodology for the Direct Introduction of Cyclic Diketone Residue into the 1,2,4-Triazine Ring FORENAME = D. N.

3-R-6-Phenyl-1,2,4-triazine 4-oxides react with cyclic β-diketones (dimethylbarbituric acid, dimedone, and indan) in both acidic (substrate activation) and basic conditions (nucleophile activation) with formation of σH-adducts, intermediates in the nucleophilic substitution of hydrogen (SN H) in 3-R-5-Nu-4-hydroxy-6-phenyl-4,5-dihydro-1,2,4-triazines. Oxidative aromatisation of these intermediates or auto-aromatisation of acylated (benzoyl chloride) at the NOH σ-adducts with elimination of benzoic acid gave the corresponding substituted 1,2,4-triazine 4-oxides or 1,2,4-triazines.

Reactions of 1,2-Diketones with Vinyllithium: Addition Reactions and Dianionic Oxy Cope Rearrangements of Cyclic and Acyclic Substrates

Dianionic oxy Cope rearrangements have been shown to take place at low temperature upon syn double addition of alkenyllithium derivatives to cyclobutanedione compounds such as benzocyclobutenedione chromium complex 1 or squaric acid esters. In order to obtain some insight into the more general applicability of this type of reaction sequence beyond these special cases, a number of 1,2-diketones were treated with vinyllithium. The diketones tested include benzil derivatives, aliphatic acyclic 1,2-diketones, ortho-quinones, and cyclic aliphatic 1,2-diketones. With benzil and heterobenzil derivatives, the desired double addition/dianionic oxy Cope rearrangement was found to take place at low temperature, leading to 1,6-diketones and their intramolecular aldol adducts in up to 80% overall yield. With acyclic aliphatic 1,2-diketones as substrates, this reaction sequence was also found, albeit with somewhat lower yields and requiring higher temperatures than in the benzil cases. A brief investigation of the intramolecular aldol adduct/1,6-hexanedione equilibrium indicated that the preferential formation of intramolecular aldol adducts at lower temperatures and at shorter reaction times appears to be the result of kinetic reaction control, whereas the preference for 1,6-diketones at higher temperatures is caused by thermodynamic reaction control. ortho-Quinones reacted with vinyllithium only by addition; no dianionic oxy Cope rearrangement was observed. This was also the case for most aliphatic cyclic diketones; however, in the case of 1,2-indanedione, rearrangement products were obtained in moderate yield at elevated reaction temperatures.

ChemInform Abstract: A New Method for Synthesizing Fluorinated Open Chain β-Enamino Ketones and Cyclic β-Enamino Diketones Using Perfluoroalkanoyl Fluorides and Ketimines.

ChemInform Abstract: A New Method for Synthesizing Fluorinated Open Chain β-Enamino Ketones and Cyclic β-Enamino Diketones Using Perfluoroalkanoyl Fluorides and Ketimines.

Structure-Reactivity-Spectra Correlations for Substituted 3,4-Diphenylcyclobut-3-ene-1,2-diones

The infrared absorption bands of the C*O stretching vibration and the 13C NMR chemical shifts were measured for a series of nine substituted 3,4-diphenyl-cyclobut-3-ene-1,2-di-ones in CHCl3, CDCl3, and partially in CCl4. The AM1 charge densities, bond orders, and valence angles were calculated for the optimized geometry. Good to satisfactory mutual correlations were found between the arithmetic means of the wave numbers of symmetric and asymmetric C*O stretching vibrations, Hammettσ constants, rate coefficients, and enthalpies of activation of the base-catalyzed ring fission as well as the AM1 oxygen charge densities and bond orders at the carbonyl groups. The results show that the factors controlling the reactivity of these compounds and the structural and IR spectroscopic properties of the C*O groups must be the same. The correlation between the wave numbers of symmetric and asymmetric C*O stretching vibrations affords a slope of a=1.069 which points to the existence of a strong cross-conjugation effect in the cyclobutenedione ring. The correlation of the wave number separation of the absorption bands of symmetric and asymmetric C*O stretching vibrations (Δv(C*O)) for various cyclic diketones enabled the prediction of the angle γ=83° between the bond vectors of the two carbonyl groups in the cyclobutenedione rings, which is in satisfactory agreement with the value calculated by the semiempirical AM1 method.

Latent Fingerprint Visualization by 1,2-Indanedione and Related Compounds: Preliminary Results

Abstract A number of vicinal cyclic diketones, most of them belonging to the 1,2-indanedione series, have been prepared and tested as potential reagents for latent fingerprint development. Unsubstituted 1,2-indanedione and a number of its mono- and dimethoxy- derivatives exhibited excellent properties as fluorogenic reagents for latent prints on paper. Structural modifications, such as substitutions at position 3, omission of the benzene ring or increase of the five-membered to a six-membered ring, considerably reduced this activity. Quite surprisingly, benzo[f]indane-1,2-dione, which was synthesized for the first time in this work, was significantly inferior to 1,2-indanedione as a fingerprint reagent. Even at this stage, before optimization of the reaction conditions, it can be said that some 1,2-indanediones are at least as sensitive as DFO. Their solubility in nonpolar solvents and relative case of preparation are further advantages. It is the authors' opinion that 1,2-indanedione itself may soon become a practical fingerprint reagent.

Fracture-induced and thermal decomposition of NTO using laser ionization mass spectrometry

A surface analysis by laser ionization (SALI) apparatus has been used to obtain, for the first time, real-time photoionization mass spectra of the shear-induced molecular-fragment emission from an explosive. NTO (5-nitro-1,2,4-triazol-3-one) was chosen for these experiments because of its potential utility as a reasonably energetic, but very insensitive, explosive. Using vacuum ultraviolet single-photon ionization, the shear-induced NTO spectra were obtained with a spring-driven shearing device installed in a SALI chamber directly beneath the mass spectrometer sampling region. For comparison, we also obtained spectra under either slow-heating or rapid pulsed-laser heating conditions. The shear-induced spectra are dominated by a peak at m/z 99, which is not seen in the thermal- or laser desorption spectra. This peak is assigned to the closed-shell traiza-diketone produced by a nitro-nitrite rearrangement, followed by NO loss and then by rapid bimolecular H-atom removal. The stability of the cyclic diketone intermediate thus generated could help to explain the shock insensitivity of NTO. Laser-desorption spectra were also obtained both on fresh NTO samples and on samples that have been recovered from marginally sub-critical drop-weight impact tests. Comparison of spectra obtained with and without laser desorption, and as a function of temperature, demonstrate that the sequences of fragment ions observed under laser desorption conditions are the result of thermal decomposition, not of ion-fragmentation. The sequence of thermally generated fragments is dominated by M-16, M-30, M-45, M-46, and M-59. This series suggests several decomposition pathways, dominated by the same nitro-nitrate rearrangement and NO loss as the shear-induced decomposition. However, under the lower-density, but higher temperature, thermal or laser-desorption conditions, subsequent bimolecular H-atom removal to produce the closed-shell diketone is evidently slower than unimolecular ring-opening adjacent to the carbonyl group. We show how this sequence satisfactorily explains (1) the “initial” formation of CO 2 that has been previously reported, (2) the results of nitrogen double-labeling experiments, and (3) the fact that neither NO 2 nor HONO have been seen as substantial initial products of NTO decomposition.

Preparation of Silyl Enol Ethers by the Reaction of Ketones with Silylamines and Methyl Iodide

Transformation of ketones to silyl enol ethers using (trimethylsilyl)diethylamine and methyl iodide is described. Both cyclic and acyclic ketones gave silyl enol ethers in high yield, whose stereochemistry showed that the formation of thermodynamically stable isomers was favored. A cyclic diketone, 1,4-cyclohexanedione, gave a 1:1 mixture of 1,4-bis((trimethylsilyl)oxy)-1,3-cyclohexadiene and 1,4-bis((trimethylsilyl)oxy)-1,4-cyclohexadiene, while 1,3-cyclohexanedione gave 3-((trimethylsilyl)oxy)-2-cyclohexenone alone. The tert-butyldimethylsilyl enol ethers of ketones also were obtained in high yield when (tert-butyldimethylsilyl)diethylamine, combined with methyl iodide, was used. A combination of allyl bromide and (trimethylsilyl)diethylamine was also effective for the transformation of ketones to silyl enol ethers.

Permanganate Chemical Oscillators with Cyclic Diketones

Permanganate chemical oscillators with 1,3-cyclopentanedione, 1,3-cyclohexanedione and dimedone (5,5-dimethyl-1,3-cyclohexanedione) in a CSTR (continuous-flow, stirred tank reactor) are described. The oscillatory systems under study are remarkable in that the oscillations are well developed, but no kinetic bistability has been found. Presumably, bistability may not be a pre-requisite for oscillations to occur.