P-Diketones synthesis

Figure 2.37 Molecular structure of [Ho3(L )3(iX3-OH)2(H20)4Cl2]Cl2 showing 30% ellipsoids with all H atoms and lattice solvent molecules removed [43]. (Reproduced with permission from RC. Andrews, G.B. Deacon, R. Frank, B.H. Fraser, P.C. Junk, et al., Formation of Ho trinuclear clusters and Gd " monodimensional polymers induced by ortho and para regioisomers of pyridyl-functionalised P-diketones synthesis, structure, and magnetic properties, European Journal of Inorganic Chemistry, 2009, 6, 744-751. Wiley-VCH Verlag GmbH Co. KGaA.)...

Andrews, P.C., Deacon, G.B., Frank, R., et al. (2009) Formation of Ho trinuclear clusters and Gd monodimensional polymers induced by ortho and para regioisomers of pyridyl-functionalised P-diketones synthesis, structure, and magnetic properties. European Journal of Inorganic Chemistry, 744-751. 

An early example was based on Cohens P-diketone synthesis (Scheme 1.6.11) and involved treatment of product 23 with a hydrazinium cation exchange resin to generate pyrazole 26. ... 

Dicarbonyl compounds have been used as ring-closure intermediates, for example in the p-diketone synthesis in Equation (4) <87CBii5l> and formation of the selenadiazepine from the bis-acetophenone shown in Equation (7) <72JHC1427>. 

Caller MA, Liao WS (2002) First Total Synthesis of a Natural Product Containing a Chiral, P-Diketone Synthesis and Stereochemical Reassigrrmort of Siphonarienedione and Siphonar-ienolone. J Am Chem Soc 124 13127... 

V. Kumar, R. Aggarwal and S. P. Singh, Reaction of Hydrazines and Hydroxylamine with Trifluorometyl-P-diketones Synthesis of Trifluoro-methylpjrazole and Isoxazole Derivatives , Heterocycles, 2008, 75, 2893. 

Tris(2,4-pentanedionato)iron(III) [14024-18-1], Fe(C H202)3 or Fe(acac)3, forms mby red rhombic crystals that melt at 184°C. This high spin complex is obtained by reaction of iron(III) hydroxide and excess ligand. It is only slightly soluble in water, but is soluble in alcohol, acetone, chloroform, or benzene. The stmcture has a near-octahedral arrangement of the six oxygen atoms. Related complexes can be formed with other P-diketones by either direct synthesis or exchange of the diketone into Fe(acac)3. The complex is used as a catalyst in oxidation and polymerization reactions. 

COMBES Quinoline Synthesis Quinoline synthesis from anilines and p-diketones... 

The Guareschi-Thorpe pyridine synthesis is closely related to the Hantzsch protocol. The primary point of difference lies in the use of cyanoacetic esters. This modification assembles pyridine 23 by the condensation of acetoacetic esters 21 with cyanoacetic esters 22 in the presence of ammonia. A second variation of this method involves reaction of cyanoacetic ester 22 with P-diketone 24 in the presence of ammonia to generate the 2-hydroxypyridine 25. 

The reduction of pertechnetate with concentrated hydrochloric acid finally yields the tetravalent state, and no further reduction to the tervalent state takes place. Therefore, the tervalent technetium complex has usually been synthesized by the reduction of pertechnetate with an appropriate reductant in the presence of the desired ligand. Recently, the synthesis of tervalent technetium complexes with a new starting complex, hexakis(thiourea)technetium(III) chloride or chloropentakis(thiourea)technetium(III) chloride, has been developed. Thus, tris(P-diketonato)technetium(III) complexes (P-diketone acetylacetone, benzoyl-acetone, and 2-thenoyltrifluoroacetone) were synthesized by the ligand substitution reaction on refluxing [TcCl(tu)5]Cl2 with the desired P-diketone in methanol [28]. 

Hydride and 1,2-alkyl shifts represent the most common rearrangement reactions of carbenes and carbenoids. They may be of minor importance compared to inter-molecular or other intramolecular processes, but may also become the preferred reaction modes. Some recent examples for the latter situation are collected in Table 23 (Entries 1-10, 15 1,2-hydride shifts Entries 11-15 1,2-alkyl shifts). Particularly noteworthy is the synthesis of thiepins and oxepins (Entry 11) utilizing such rearrangements, as well as the transformations a-diazo-p-hydroxyester - P-ketoester (Entries 6, 7) and a-diazo-p-hydroxyketone -> P-diketone (Entry 8) which all occur under very mild conditions and generally in high yield. 

It is quite often possible to prepare hydroxypyridinone complexes directly by one-pot synthesis from the appropriate hydroxypyranone, amine, and metal salt 90-92). They can also be prepared by reacting complexes such as P-diketonates with hydroxypyridinones (see e.g., Ce, Mo later). Several maltolate complexes, of stoichiometry ML2, ML3, ML4, or MOL2, have been prepared by electrochemical oxidation of the appropriate metal anode, M — a first-row d-block metal (Ti, V, Cr, Mn, Fe, Co, Ni), In, Zr, or Hf, in a solution of maltol in organic solvent mixtures 92). Preparations of, e.g., manganese(III), vanadium(III), or vanadium(V) complexes generally involve oxidation... 

The sol-gel method of preparing lithium niobate used lithium and niobium alkoxides. Alkoxides are often used in CVD methods, but unfortunately for the preparation of lithium niobate, lithium alkoxides are much less volatile than niobium alkoxides and to get the two metals deposited together it is better to use compounds of similar volatility. One way around this problem is to use a more volatile compound of lithium. One reported synthesis uses a p diketonate of lithium in which lithium is coordinated to 2,2,6,6-tetramethylheptan-3,5-dione (Me3CCOCH2COCMe3) (Figure 3.11). 

The products of partial substitution for the OR-groups, i.e., alkoxocarbox-ylates, P-diketonates M(OR)mX , where X= RCOO, acac, thd, etc.—the mixed-ligand complexes—usually are more soluble and stable than M(OR) , as their molecules contain the chelate cycles. Mehrotra et al. [223] have described a great number of such products (usually liquid or amorphous), in which individuality appeared sometimes questionable. During recent years, however, in connection with the application of these compounds to the synthesis of oxides, interest in them has increased, and a number of them have been isolated and structurally characterized (Chapter 7). Unfortunately, length restriction did not permit us to present a complete review of their chemistry in this book. 

The interaction of the metal alkoxides with the salts of carboxylic acids or with p-diketonates of other metals is especially attractive for the synthesis of bimetallic molecular precursors in the cases, when the preparation of the alkoxide of the other metal is somehow hindered or it is insoluble or irreactive under the conditions applied. This method has been widely used for the sol-gel preparation of HTSC materials (because of low solubility and reactivity of Cu(OR)2) and lead-containing ferroelectrics (in the view of difficult synthesis and low stability of Pb(OR)2). It should be mentioned that the reaction between a metal alkoxide and a functional derivative does far not always lead to the formation of a mixed-ligand bimetallic complex ... 

A large class of coordination compounds, metal chelates, is represented in relation to microwave treatment by a relatively small number of reported data, mainly p-diketonates. Thus, volatile copper) II) acetylacetonate was used for the preparation of copper thin films in Ar — H2 atmosphere at ambient temperature by microwave plasma-enhanced chemical vapor deposition (CVD) [735a]. The formed pure copper films with a resistance of 2 3 pS2 cm were deposited on Si substrates. It is noted that oxygen atoms were never detected in the deposited material since Cu — O intramolecular bonds are totally broken by microwave plasma-assisted decomposition of the copper complex. Another acetylacetonate, Zr(acac)4, was prepared from its hydrate Zr(acac)4 10H2O by microwave dehydration of the latter [726]. It is shown [704] that microwave treatment is an effective dehydration technique for various compounds and materials. Use of microwave irradiation in the synthesis of some transition metal phthalocyanines is reported in Sec. 5.1.1. Their relatives - porphyrins - were also obtained in this way [735b]. 

A detailed spectroscopic study of uranyl acetylacetonate [337-339] and other p-diketonates [339], as well as uranyl /u. v-(2-hydroxy-1 -naphthaldchyde) [U02(2H1N)2] [340] and uranyl fe-(2-hydroxybenzaldehyde) [341] was carried out. On the basis of the data obtained, the following structure was assigned to uranyl /u. v-(2-hydroxy-l-naphthaldehyde) [U02(H1N)2] 973 [340] (with permission), whose synthesis was described earlier [342] ... 

De Nicola, A. J., and Bell, J. P., Synthesis and Testing of p-Diketone Coupling Agents for Improved Durability of Epoxy Adhesion to Steel, in Adhesion Aspects of Polymeric Coatings, K. L. Mittal, ed., Plenum Press, New York, 1983, p. 443. 

Base catalysis is not required for conjugate addition. If the nucleophile is sufficiently enolized under the reaction conditions then the enol form is perfectly able to attack the unsaturated carbonyl compound. Enols are neutral and thus soft nucleophiles favouring conjugate attack, and p-dicarbonyl compounds are enolized to a significant extent (Chapter 21). Under acidic conditions there can be absolutely no base present but conjugate addition proceeds very efficiently. In this way methyl vinyl ketone (butenone) reacts with the cyclic P-diketone promoted by acetic acid to form a quaternary centre. The yield is excellent and the triketone product is an important intermediate in steroid synthesis as you will see later in this chapter. 

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