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1.3- Dike tone

Although the most recent modifications of the Prelog condensation of 1,3-dike-tones and 1,3,5-triketones, for example that of acetylacetone with dimethyl 1,3-acetonedicarboxylate in the presence of NaOH in H2O, afford substituted benzenes such as 1486 in up to 94% yield (Scheme 9.22) and coumarins [40], these condensations of highly substituted polyketones with the corresponding aromatic systems might also be effected in the presence of HMDS 2/TCS 14 or TMSOTf... [Pg.226]

Carbazole-1- and carbazole-3-amino groups have been diazo-and the diazonium salts coupled with 1,3-dike-tones and ethyl acetoacetate, used in Sandmeyer reactions, reduced to the hydrazines and made to effect intramolecular arylation of a 9-aryl group, such as in the transformation of 215 (R = Me or C02Me) into 216 (R = Me or C02Me). It is worth repeating the earlier observation... [Pg.156]

This, the most widely used route to pyrazoles and isoxazoles rests on the doubly nucleophilic character of hydrazines and hydroxylamine, allowing them to react in turn with each carbonyl group of a 1,3-dike-tone or 1,3-keto-aldehyde, often with one of the carbonyl groups (especially when aldehyde) masked as enol ether,acetal, imine or enamine, or other synthon for one of these. [Pg.494]

Inspired by their previous work dealing with enantioselective conjugate addition of t-butyl acetoacetate to crotonoylthiazolidinethione catalysed by a preformed nickel catalyst from/>-To 1-BINAP ligand 30, and by those of Kane-masa on enantioselective nickel-catalysed additions of thiols and 1,3-dike-tones to unsaturated acylpyrazoles and oxazolidinones with a chiral amine ligand, Evans et al. investigated the scope of enantioselective Michael... [Pg.73]

Closely related to some of the complexes in Scheme 11 are the structures of Pd(dtbpx)( 7 -qn), [Pd(PPh3>2-(77 -qn)] 2H2qn, Pd2( 7, 77 -qn)2(PPh3)2, Pd(bipy)( 7 -qn), and Pd l,2-bis(A-(4-methylphenyl)imino)acenaphtene -Also closely related is complex II, involving a cyclohexenone, which was prepared by two methods in the course of a mechanistic study of the palladium-catalyzed intramolecular cyclization of alkadienyl-substituted 1,3-dike-tones (Scheme 12). ... [Pg.323]

The equivalence of silyl enol ethers and ends has been used in syntheses of -halogeno-a -unsaturated ketones, /8-keto-sulphidesand 1,3-dike-tones (Scheme 94) the 1,3-diketone (39) prepared in this manner forms a europium complex of high solubility in non-polar solvents. [Pg.175]

In the Diels-Alder reaction with inverse electron demand, the overlap of the LUMO of the 1-oxa-l,3-butadiene with the HOMO of the dienophile is dominant. Since the electron-withdrawing group at the oxabutadiene at the 3-position lowers its LUMO dramatically, the cycloaddition as well as the condensation usually take place at room or slightly elevated temperature. There is actually no restriction for the aldehydes. Thus, aromatic, heteroaromatic, saturated aliphatic and unsaturated aliphatic aldehydes may be used. For example, a-oxocarbocylic esters or 1,2-dike-tones for instance have been employed as ketones. Furthermore, 1,3-dicarbonyl compounds cyclic and acyclic substances such as Meldmm s acid, barbituric acid and derivates, coumarins, any type of cycloalkane-1,3-dione, (1-ketoesters, and 1,3-diones as well as their phosphorus, nitrogen and sulfur analogues, can also be ap-... [Pg.161]

Triheteroaryls are obtained from /(-dike tones (such as 83) from 3-acetyl-selenophene condensed with suitable methyl esters.94 However, it was... [Pg.150]

In 1968 the first reports of spin crossover in iron(III) monothio-y8-diketo-nates appeared [84, 85] and reviews on metal complexes of monothio-/ -diketones were published shortly afterwards [86, 87]. The monothio-/ -dike-tones can be considered as a ligand system intermediate between acetylace-tone and dithioacetylacetone (Fig. 4). [Pg.289]

Titanacyclobutanes also serve as useful synthetic intermediates the titanacycle 43, prepared by the intramolecular reaction of the alkenylidene complex 44, affords the a-dike-tone 45 and the other functionalized cyclic compounds by further transformations (Scheme 14.20) [35]. [Pg.485]

The Sm-catalyzed synthesis of a-dike-tones from aromatic esters [571], the... [Pg.588]

MECER A process for recovering copper from waste streams by extraction with a p-dike-tone solution. Used in Germany, Sweden, the United Kingdom, and the USSR for treating effluent from the etching of printed circuit boards. [Pg.166]

Alkylation of I -dike tones with allylic and benzylic alcohols. Allylic and benzylic alcohols can alkylate 1,3-dikcloncs and other active hydrogen compounds in the... [Pg.101]

The planar configuration of quadricovalent copper(Il) was discovered by Cox and Webster21 in the compounds of copper with 0-dike-tones (copper disalicyl ldoxime, copper acetylacetonate, copper ben-zoylacetonate, the copper salt of dipropionylmethane) and by Tunell, Posnjak, and Ksanda22 in the mineral tenorite, CuO. In crystalline cupric chloride dihydrate (Fig. 5-9) there are molecules with the planar configuration23... [Pg.158]

Surface lipids of plants. The thick cuticle (Fig. 1-6) that covers the outer surfaces of green plants consists largely of waxes and other lipids but also contains a complex polymeric matrix of cutin (stems and leaves) or suberin (roots and wound surfaces).135/135a Plant waxes commonly have C10 - C30 chains in both acid and alcohol components. Methyl branches are frequently present. A major function of the waxes is to inhibit evaporation of water and to protect the outer cell layer. In addition, the methyl branched components may inhibit enzymatic breakdown by microbes. Free fatty acids, free alcohols, aldehydes, ketones, 13-dike tones, and alkanes are also present in plant surface waxes. Chain lengths are usually C20 - C35.136 Hydrocarbon formation can occur in other parts of a plant as well as in the cuticle. Thus, normal heptane constitutes up to 98% of the volatile portion of the turpentine of Pin us jeffreyi.81... [Pg.1196]

The Evans Cu(II)- and Sn(II)-catalyzed processes are unique in their ability to mediate aldol additions to pyruvate. Thus, the process provides convenient access to tertiary a-hydroxy esters, a class of chiral compounds not otherwise readily accessed with known methods in asymmetric catalysis. The process has been extended further to include a-dike-tone 101 (Eqs. 8B2.22 and 8B2.23). It is remarkable that the Cu(II) and Sn(II) complexes display enzyme-like group selectivity, as the complexes can differentiate between ethyl and methyl groups in the addition of thiopropionate-derived Z-silyl ketene acetal to 101. As discussed above, either syn or anti diastereomers may be prepared by selection of the Cu(II) or Sn(II) catalyst, respectively. [Pg.533]

Subramanian, M.S. Pai, S.A. Manchanda, V.K. Acid dissociation of some beta dike-tones in mixtures of water and dioxane - A thermodynamic study, Aust. J. Chem. 26 (1973) 85-89. [Pg.109]

Manchanda, V.K. Subramanian, M.S. IR and PMR studies of some uranyl beta-dike-tones oxodonor adducts, Acta Chim. Acad. Sci. Hung. Ill (1982) 63-67. [Pg.109]

Thiophenecarbaldehydes add smoothly to a,(3-unsaturated ketones and nitriles under cyanide ion catalysis to form y-dike tones (366) and y-ketonitriles (367) respectively (76CB534). The 2,5-dicarbaldehyde gives the bis-adduct (368). The aldehydes undergo normal reduction to the hydroxymethylthiophenes by sodium borohydride. However, electrochemical reduction of the 2,5-dialdehyde on a mercury electrode at pH 1-3 gives the bimolecular reduction product (369) as a mixture of meso- and ( )-forms in the ratio 7 3. Reduction with zinc and acetic acid gives only the meso -form of (369) (75CR(C)(280)165). [Pg.808]

The 2-alkyl group of 2-alkylisoxazolium salts is also susceptible to a -deprotonation. For example, treatment of 3,5-distyrylisoxazo.lium salt (199) with potassium methoxide followed by acid hydrolysis gave the natural /3-dike tone curcumine (77H(7)24l). [Pg.51]

Though the cyclization looks awkward—the product is a bridged bicyclic dike tone—the alternative would give a strained four-membered ring and does not occur. [Pg.740]

The catalytic approach to conjugate addition is illustrated by the addition of a (3-dike tone to an aromatic enone catalysed by potassium hydroxide and benzyltriethylammonium chloride, which is a phase transfer catalyst. Once again, the catalytic cycle is initiated by deprotonation of the most acidic component in the reaction mixture, acetyl acetone, which is followed by a cycle of conjugate addition and proton exchange leading inexorably to the product. [Pg.753]

This is a good general method for the synthesis of 1,4-dike tones, which can be otherwise difficult to make, and additional substituents are easily accommodated on the enone—a characteristic of conjugate addition. [Pg.767]

Selenophene /3-diketones can be used as extractants for the separation and isolation of metals. The advantages of selenophene /3-dike-tones were revealed by comparison of their dissociation and distribution constants with those of acetylacetone, benzoylacetone, thenoyl-trifluoromethylacetone, etc. Selenophene /3-diketones containing a trifluoromethyl group and a pyridyl radical were of particular interest. 2-Acetoacetylselenophene127 is better for the extraction of thorium from water than acetylacetone, previously extensively used. [Pg.39]

Unlike moat fi dike tones, the foUo eing diketooc has no detectable enol CMUent and is about as acidic as acetone. Explain... [Pg.927]

Monothio -diketones can be prepared by the action of hydrogen sulfide and hydrogen chloride on the appropriate -diketone in alcohol solution. Nevertheless the conditions are rather critical. At room temperature -dike-tones are in tautomeric equilibrium between the diketo form (I) and the chelated hydrogen-bonded form (II), and in polar solvents the concentration of the diketo form (I) is increased. Reaction with hydrogen sulfide occurs only with the diketo tautomer (I). Consequently, higher concentrations of hydrogen chloride are required for those -diketones which exist predominantly in the... [Pg.207]

The Kolbe reaction of pyruvic acid and phenylglyoxylic acid (XIV) (R = CH3 and Ph) affords the corresponding diketones (XV) in high yields [Eq. (12)] [58,59]. Interestingly, electroluminescence can be observed during the electrolysis, which probably can be attributed to phosphorescence due to the generation of excited triplets of a-dike-tones in the acyl radical recombination. [Pg.507]


See other pages where 1.3- Dike tone is mentioned: [Pg.550]    [Pg.34]    [Pg.1188]    [Pg.1188]    [Pg.1295]    [Pg.1069]    [Pg.550]    [Pg.68]    [Pg.234]    [Pg.821]    [Pg.720]    [Pg.103]    [Pg.110]    [Pg.206]    [Pg.295]    [Pg.1195]    [Pg.40]    [Pg.1077]    [Pg.530]    [Pg.1187]    [Pg.1187]    [Pg.34]    [Pg.347]    [Pg.396]    [Pg.81]   
See also in sourсe #XX -- [ Pg.6 , Pg.20 , Pg.32 ]




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Dikes

Diking

Tones

Toning

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