With 1,3-Diketones

4-Dioxopentane, its 1,5-di-n-alkyl-substituted derivatives, and its derivatives with one or two alkyl groups on the carbon atom joining the two carbonyl groups, condense with tellurium tetrachloride in refluxing chloroform to produce 3,5-dioxotellurane 1,1-dichlorides. The reaction does not proceed with l,l-dialkyl-2,4-dioxopentanes, 1,1,5,5-tetraalkyl-2,4-dioxopentanes, or with l,5-diisopropyl-2,4-dioxopentane. 

Starting Material 3,5-dioxo-... tellurane 1,1-dichlorides Yield [%] m. p. rc] Refer- ence 

5-Dioxotelluranc 1,1-Dichloride In a 250 ml flask fitted with a reflux condenser are placed 10.3 g (38 mmol) of tellurium tetrachloride, 7.6 g (76 mmol) of acetylacetone, and 55 ml of chloroform and the mixture is heated under reflux on a boiling water bath for 2 h. The heavy grey oil is decanted, the decantate is filtered, and the filtrate is placed in a dessicator charged with calcium chloride. As the solvent evaporates, the product crystallizes. The crystals are collected and recrystallized from benzene yield 7 g (62%) m.p. 169-173° (dec.). 

The condensation reactions between tellurium tetrachloride and 2,4-dioxopentanes produce, in addition to the cycUc products, bis[2,4-dioxopent-l-yl] tellurium dichlorides which are difficult to isolate from the mother liquor. Such tellurium dichlorides were also obtained from 2,4-dioxopentane derivatives not eapable of condensation to heterocycles. 

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Table 27 Mn Compounds with 0-Diketonate Type Ligands...

A number of organic compounds, eg, acetylacetone [123-54-6] and cupferron [135-20-6] form compounds with aqueous actinide ions (IV state for reagents mentioned) that can be extracted from aqueous solution by organic solvents (12). The chelate complexes are especially noteworthy and, among these, the ones formed with diketones, such as 3-(2-thiophenoyl)-l,l,l-trifluoroacetone [326-91-0] (C4H2SCOCH2COCF2), are of importance in separation procedures for plutonium. 

The use of 2-substituted amino-3-aminopyridines (or corresponding 3-substituted amino-2-amino, 3-substituted amino-4-amino and 4-substituted amino-3-amino derivatives) gives the corresponding TV-substituted pyridopyrazinones with esters or alloxan, or with diketones gives quaternary salts such as (403) or their anhydro bases (404) e.g. 56CB2684, 78HCA2452). 

Intramolecular Claisen condensations can be carried out with diesters, just as intramolecular aldol condensations can be carried out with diketones (Section 23.6). Called the Dieckmann cyclization, the reaction works best on 1.6-diesters and 1,7-diesters. Intramolecular Claisen cyclization of a 1,6-diester gives a five-membered cyclic /3-keto ester, and cyclization of a 1,7-diester gives a six-membered cyclic /3-keto ester. 

Platinum(IV) ammines react with diketones to give diimmines, a reaction proceeding via deprotonation of one ammonia [167],... 

OS 52] [R 4b] [P 38] See discussions in the preceding and following sections [8]. Reactivity of different substrates with diketone moieties... 

OS 52[ [OS 53[ [OS 54[ [OS 55[ [R 4b[ [P 38[ In a two-micro-mixing tee chip reactor, substrates with diketone moieties of known different reactivity, such as 2,4-pentanedione, benzoylacetone and diethyl malonate, were processed, each with the same acceptor ethyl propiolate [8]. Also, a reaction with the less alkynic Michael acceptor methyl vinyl ketone was carried out. 

Cycloaddition reactions of phosphines with diketones have continued to be exploited in the synthesis of five-coordinate spirophosphoranes. 

Several 3-mercapto-l,2,4-trizines have been synthesized through the condensation of thiosemicarbazide with diketones under microwave irradiation in a solventless system <06PS87>. The synthesis and cyclocondensation reactions of 3-substituted-5-(2-aminobenzyl)-l//-[l,2,4]triazin-6-ones have been reported <06JHC613>. 

Pyridone formation from the condensation of cyanoacetic ester with diketone in the presence of ammonia. 

Regioselective synthesis of 2-substituted pyrroles using oximinocyanoacetate esters or related compounds in a Knorr-type reductive condensation with diketones was described . Thus, oximinocyanoacetates 63 reacted with pentane-2,4-diones 64 in hot... 

The preferred route for reducing the molecular weight of PVA involves chain scission at the 1,3-diketone site (see Fig. 6). As the diketone element is chemically not very stable, a spontaneous degradation of oxidised PVA was also discussed [80]. Nevertheless, the preferred degradation pathway is most likely the biochemical process because enzymes were identified that showed high activity with diketone substrates [81], especially with oxidised PVA. The p-diketone hydrolase (BDH EC 3.7.1.7) hydrolyses aliphatic p-diketones to form methyl ketones and carboxylic acids in equimolar amounts [82]. The enzymatic cleavage of C-C bonds in p-diketones is not well studied [83]. BDH enzymes could be isolated from different PVA-degrading strains, purified, characterised and cloned [84]. 

Amino-l-(p-toluenesulfonyl)pyrazole condenses with -diketones to yield acylaminocrotonate derivatives. These cyclize to pyrazolo[l,5-a]pyrimidines... 

The principle of condensation with diketones has further been extended by using 1,3-diketones to form 2,4-disubstituted quinolizines.14 In general the reaction involves the condensation of 2-picolyllithium with the enol ether or the monoketal of a /3-dicarbonyl compound followed by cyclodehydration of the resulting carbinol by means of acid. This scheme is illustrated in Eq. (5). 

Complexes with -diketones, tropolonates, catecholates, quinones and related ligands 142... 

Metal alkoxides constitute a useful class of starting materials for the synthesis of the metal / -diketonates. The ethoxides of Nbv, Tav and Uv react with diketones. Here, only partial substitution of the ethoxy groups occurs and materials of the type M(diketonate)3(OEt)2 are formed.194,195 Similar reactions with lanthanide alkoxides, however, provide pure, unsolvated lanthanide tris(diketonates). The virtue of such syntheses lies in their ability to yield anhydrous diketonate complexes. Removal of water from the hydrates without decomposition is sometimes difficult.196,197... 

Potassium tetracarbonylhydridoferrate is a hydride transfer agent that may be used to reduce ketones selectively in high yields (equation 54)205. With diketones a hydroxy ketone is produced. 

A complementary application to the use of Os complexes in photovoltaic cells is the use of luminescent Os complexes in electroluminescent devices. There has been a significant amount of work in this area, particularly as it applies to the development of Os complexes with high quantum yields for phosphorescence. A review of transition metal complexes used in OLED development was published in 2006 by Evans et al. [126]. Another very recent review discusses various Os(II) carbonyl complexes with diketonate, hydroxyquinolate, bipyridine, and phenanthroline ligands as emitters in OLED devices [127]. A few select examples of Os complexes in OLEDs are presented here. 

Bistperfluoroalkylsulfonylaminates) bear some resemblance with diketonates and their Ndm complexes with alkyl chain length ranging from 1 to 8 have been measured in deuter-ated acetone and dmso, as well as in un-deuterated acetone. While all these complexes... 

Monothiomalonic acid hydrazides (398), prepared by the reaction of cyanoacetohydrazides with H2S, react with diketones (e.g. (397)) to give pyridine-2-thiono-3-carboxhydrazides (399) which cyclize with the loss of H2S to give 1-substituted pyrazolo[3,4-Z>]pyridin-3-ones (e.g. (400)) (Scheme 44) <85S861>. 

The condensation of amino acids esters with diketones leads to cylic derivatives. Limited success was achieved in this respect with acetyl acetone [262] amino acids were condensed prior to GC analysis with 2,5-hexanedione by Walle [263] (Scheme 5.24). The free carboxyl group of the reaction product was esterified with methanolic HC1. However, the procedure was applied to only a few amino acids. 

Pyrylium salts with a free - or -position react in a similar way without ring fission, flavylium adds dimethylaniline and the product aromatizes to give cation 312 xanthylium ions form adducts at the 9-position with -diketones, -keto esters, and malonic esters (e.g., 313). 

Condensation of 3,4-diamino-l,2,5-thiadiazole 462 with -diketones produces [l,2,5]thiadiazole[3,4- ]pyrazines 463, which are reduced to provide 2,3-diaminopyrazines 464 (Scheme 216) <1997JCM250, CHEC-III(8.03.10)313>. 

Ketone 13 is apparently sensitive to overoxidation and the reaction mixture must be cooled to -78 °C before ozone is bubbled through it. Ozone addition must be stopped immediately after the blue colour of the ozone-saturated solution is detected. Another potential side reaction is the condensation of benzaldehyde with diketone 12 this reaction can be induced by overheating a concentrated solution of the crude product mixture. Accordingly, the residue from rotary evaporation obtained in step 10 of Protocol 7 should not be heated above 45-50 °C before benzaldehyde is removed completely by exposure to high vacuum and trituration of the residue with diethyl ether. 

Lanthanide complexes with diketones and Schiff bases.266... 

Lewis bases like aliphatic or aromatic amines, sulphoxides, phosphorous derivatives form adducts with / -diketonates, by recrystallization of the hydrated lanthanide fi-diketonates in a solution of the substrate [51,52]. The adducts have also been prepared by extraction of lanthanide salt with a stoichiometric mixture of the /5-diketone and a Lewis base. Alternatively it can be prepared by increasing the pH of an ethanolic-water solution of lanthanide salt, /5 -diketone and the organic substrate. 

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