Cyclic Β-diketones Research Articles

Synthesis of derivatives of some condensed systems that include furan rings and investigation of them by the lanthanide-shift-reagent method

Derivatives of some condensed systems that include furan rings were obtained by condensation of 1,4-benzoquinones with cyclic β-diketones under the conditions of the Michael reaction. The structure of the methoxy derivatives of tetrahydrobenzofuran were established from the PMR spectra with the aid of europium(III) tris(1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedionate). The location of the europium ion in the adduct of the lanthanide shift reagent (LSR) with the substrate was determined.

The BF3 Catalyzed Decomposition of Diazo Compounds in the Presence of Carbonyl Compounds

Abstract The BF3 catalyzed decomposition of diazo ompounds such as α-diazoacetophenones, ethyl diazoace-tate, and diphenyldiazomethane in the presence of cyclic β-diketones gave the corresponding enol ether. Used as a substrate, cyclohexanone gave the ring expanded homologation product.

Bicyclo[4.2.1]non-1-en-8-one; a novel anti-Bredt enone. Synthesis of non-enolisable β-diketones from oxo-acids

Several cyclic β-diketones were prepared by acid-catalysed intramolecular cyclisation of appropriate oxo-acids. One of them, bicyclo[4.2.1]nonane-2,8-dione, was converted into the bridgehead enone named in the title. Some reactions of this compound are reported. Reaction of (5R*,6R*)-6-tosyloxyspiro[4,4]nonan-1-one with boiling collidine gave 1,2,3,5,6,7-hexahydroinden-4-one by elimination and rearrangement.

The Preparation and Properties of Some Cyclic β-Diketone Diimines

The condensation reaction between a series of aliphatic diamines and a series of five- and six-membered cyclic β-diketones to form Schiff bases was investigated. Mass spectral data show that reaction occurred on the side-chain carbonyl except where steric hindrance forced condensation to occur on the ring carbonyl. N.m.r. studies show that these Schiff bases exist primarily in the ketamine form in solution, irrespective of the solvent. I.r. data confirm this. The preparation of a number of Cu(II) and Ni(II) complexes from some of the ligands is also described.

Reaction of benzisoxazolium cations with cyclic β-diketones

Reaction of 2-ethylbenzisoxazolium fluoborate (III) with dimedone, dihydroresorcinol, 2-methyldihydroresorcinol and 2-methylcyclopentane-1,3-dione in the presence of base leads to the formation of amides VIII, XI, X and XIII respectively, via the benzoketoketenimine intermediate (IX) and an intramolecular migration. The 7-hydroxy-2-ethylbenzisoxazolium salt (IV) gives the amide (XIV) by double migration. Amides VIII, XI, X and XIII undergo intramolecular Michael reaction to furnish the benzoxazinones (XVI, XVIII, XVII and XXVI). Stereochemistry of this addition is discussed and the conformation in which the CN bond at C-1′ is attached equatorially to the cyclohexanone ring is assigned to the Spirans (XX, XXX and XXVIII). Effect of acids and bases on the amide (VIII) and the spiran (XVI) is described.

Additions and Corrections - vic-Cyclopropanediols from Lithium in Ammonia Reductions of Cyclic β-Diketones

Additions and Corrections - vic-Cyclopropanediols from Lithium in Ammonia Reductions of Cyclic β-Diketones

Spectres de Masse d'Imides Cycliques

The mass spectra of 14 cyclic imides have been recorded. These spectra allowed us to draw following conclusions: a) The fragmentation pattern of the cyclic imides studied bear strong analogies with those previously derived from a study of cyclic β-diketones. These results suggest preferential ionization of the oxygen instead of the nitrogen atom. b) Provided metastable peaks are observed for the reactions M+· (M–RNCO)+· and M+ · C2NO2+, it is possible to differentiate imides substituted on the nitrogen atom from the unsubstituted one. The explanation for such a behaviour of cyclic imides, under electron impact, is to be found in the conjugation of molecular orbitals, as are the acidic properties of these molecules.

Reaction of cyclic beta-diketones with 3,4-dihydroisoquinolines and related compounds. Preparation and anticancer activity of 2-substituted 1,3-cyclohexanediones.

Reaction of cyclic beta-diketones with 3,4-dihydroisoquinolines and related compounds. Preparation and anticancer activity of 2-substituted 1,3-cyclohexanediones.

Chloroperoxidase: II. UTILIZATION OF HALOGEN ANIONS

Abstract Chloroperoxidase can utilize chloride, bromide, and iodide ions and catalyze the formation of a carbon-halogen bond in the presence of suitable acceptor molecules. Suitable halogen acceptor molecules are β-keto acids, cyclic β-diketones, and substituted phenols. An optical assay has been developed to measure the halogenating activity of chloroperoxidase. The assay is based on the conversion of monochlorodimedon to the corresponding gem-dihalo derivative. The optical assay is based on the loss of absorbance at 278 mµ associated with the formation of the dihalo derivative from the monohalo compound. In the optical assay, crystalline chloroperoxidase preparations catalyze the formation of the dichlorodimedon from monochlorodimedon, chloride ion, and hydrogen peroxide at a rate of 67,000 moles of product formed per min per mole of enzyme. When bromide ion replaces chloride ion in the optical assay, the rate of formation of monobromo-monochlorodimedon is approximately twice the rate of formation of dichlorodimedon. The chloroperoxidase-catalyzed halogenation of tyrosine can be followed by measuring the decrease in tyrosine fluorescence associated with the formation of the mono- and dihalogenated tyrosines. At low concentrations of halogen anion (0.33 mm) the relative activity among the halogen anions for the halogenation of tyrosine is approximately 5.1:4.8:1 for iodide, bromide, and chloride, respectively. At higher concentrations of halogen anion, 3.3 mm, the ratio of activity between bromide and chloride falls to 3:1. At 3.3 mm iodide concentration, the enzymatic formation of elemental iodine masks the tyrosine fluorescences measurements so that rate comparisons cannot be made in this instance. Crystalline chloroperoxidase preparations catalyze the chlorination of tyrosine at a rate of approximately 7500 moles of product formed per min per mole of enzyme. Fluoride is not a substrate for chloroperoxidase but is an inhibitor of the halogenation reaction. The results indicate that fluoride ion can compete for both the hydrogen peroxide- and the halogen anion-binding sites on chloroperoxidase. Chloroperoxidase shares with other peroxidases the ability to catalyze the oxidation of iodide to iodine. The rate of iodine formation is about 1.5 times the rate of chlorination of monochlorodimedon when the reactions are compared, with equivalent amounts of enzyme and under saturating conditions for all substrates.

The Reaction between Cyclic β-Diketones and Grignard Reagents. III. 2-Methyl-2-benzoylhydrindone

The Reaction between Cyclic β-Diketones and Grignard Reagents. III. 2-Methyl-2-benzoylhydrindone

The Reaction between Cyclic β-Diketones and Grignard Reagents. 1,3-Diketo-2,2-dimethylhydrindene1

The Reaction between Cyclic β-Diketones and Grignard Reagents. 1,3-Diketo-2,2-dimethylhydrindene¹

Reaction of Diazonium Salts with Hydroxymethylen cycloHexanones and Cyclic β-Diketones

Reaction of Diazonium Salts with Hydroxymethylen cycloHexanones and Cyclic β-Diketones