1,3,5,7-Tetraketones

Diketones and tetraketones derived from aromatic compounds by conversion of two or four SCH groups into keto groups, with any necessary rearrangement of double bonds to a quinonoid structure, are named by adding the suffix -quinone and any necessary affixes. 

The dicarboxylic acid chlorides from sebacic and azelaic acid react with 2 moles of enamine to give the tetraketone (117), which on base cleavage... 

Dicarboxylic acid dichlorides with less than seven carbon atoms do not react to give tetraketones similar to 117, but instead undergo an intramolecular acylation (72) to give on hydrolysis the vinylogous acid anhydride (118), e.g., from succinyl chloride and the enamine (113). 

Diaryl bisfurans are available from two sequential Paal-Knorr reactions of tetraketones. For example, Barba converted 46 into 3,3"-bis-2,5-diphenylfuran (47) in good yield upon treatment with sulfuric acid and acetic anhydride. ... 

Deligoz and Yilmaz [52] reported that the selective liquid-liquid extraction of various alkali and transition metal cations from the aqueous phase to the organic phase as carried out by using p-tert-h iy calix[4]arene (1), p-tert-b x. y calix[6]arene (2), tetra-ethyl-p-tm-butylcalix[4]arene-tetra-acetate (3), tetra-methyl-p-/< /-/-butyl calix[4]arene-tetraketone (4), calix[n]arenes ( = 4 and 6) bearing oxime groups on the lower rim (5 and 6) and a polymeric calix(4]arene (8). It was found that compounds 5 and 6 showed selectivity towards Ag, Hg, Hg, Cu, and Cr and the order of the ex-tractability was Hg > Hg > Ag > Cu > Cr. The polymeric calix[4]arene (8) was selective for Ag, Hg, and Hg , unlike its monomeric analog. 

The tetraketone can be obtained in a pure form by recrystallizing it first from ether with the addition of decolorizing carbon and then from -butanol yield 50-58% m.p. 68-72°. 

This, and the tetraketone resulting from dehydration of the gem-diol groups, both explode under a hammer blow. 

The bis(trimethylsiloxy)bicyclo[n.l.O]alkane 231 undergoes the FeCl3-induced ring expansion to the cycloalkane-1,3-dione 232. This method has been applied to the synthesis of macrocyclic tetraketones [128]. (Scheme 92)... 

The formation of the bottom structure in Scheme 3.51 seems surprising. The related semidione from l,4-dimesitylbutatetra-l,2,3,4-one (dimesityl tetraketone) forms ion pairs with Na, Cs, and Ba + but do not exhibit any chemical reactions (Bock et al. 1990). 

On treatment with IBD, tetraketones 213 are transformed to pyrones 215. This reaction probably occurs via intermediate cyclic ene-hemiacetal 214. In contrast, lead tetra-acetate (LTA), which generally behaves similarly to IBD, shows a different reactivity pattern in the oxidation of 213, thereby yielding the isomeric pyrone 216 (80TL1575 83JHC1389). 

A tetraketone, 1,4,9,10-anthradiquinone, is reduced by fermenting yeast to quinizarin ... 

Oxidation of a 1, 4,6-tetraketone (I).1 Oxidation of oxalyldiacetone (1) with iodosobenzene diacetate results in 2. Oxidation of 1 with lead tetraacetate gives dchydroacetic acid (3), previously obtained by dimerization of diketene. 

Polynuclear complexes with more than two metal ions have been prepared with polyketone ligands but no such complexes have been reported with V02+. With the tetraketone l,l -(2,6-pyridyl)-bis-l,3-butanedione (H2L), several polynuclear complexes have been prepared including [(VO)2(L)2] for which jj,Tc = 1.21 BM was obtained.908... 

One of two products- can be obtained from the tetraketone (348), tautomeric with the furanone (349), depending on the oxidant (80TL1575). Lead(IV) acetate gives the 4-hydroxy-pyran-2-one (350), whereas the pyran-4-one results from the use of iodosobenzene diacetate (Scheme 109). 

A biogenetic flavour is apparent in the formation of dihydroxybenzophenones by the reaction of o-hydroxybenzoate esters with the trianion of heptane-2,4,6-trione (81JOC2260). Acylation of the trianion occurs at 0-25 °C to give a tetraketone which cyclizes under mildly basic conditions to the corresponding benzophenone. A second ring closure takes place when the benzophenone is treated with sodium methoxide, leading to the xanthone (Scheme 188). 

Triketones are homologues of 1,3-diketones and in these, too, keto-enol tautomerism has been probed by H NMR spectroscopy.567,568 Triketones and tetraketones may coordinate to one or more metal ions per molecule. In the latter case the metal centers are held in such close proximity that, in some cases, interesting magnetic effects may be observed. Structural and magnetic properties of polynuclear transition metal jS-polyketonates have been thoroughly reviewed.569,570... 

Tetraazaporphyrin, octaphenyl-metallation, 858 Tetraazaporphyrins synthesis, 857 Tetraethylenepentamine metal complexes, 56 Tetraglycine metal complexes, 764 Tetraketones metal complexes, 399 1,3,5,7-Tetraketones metal complexes, 400 Tetramines cyclic... 

Ozonolysis of diketone carbonate 417 in methanol afforded an almost quantitative yield of the bicyclic diene triketone hydroxy-ester 418 (119). This remarkable transformation can also be readily explained. Ozonolysis of 417 produces the tetraketone intermediate 419 followed by methanol addition to produce the hemi-ketal 420 which undergoes a retro-Claisen reaction to 421. Then, loss of carbon dioxide from 421 yields 418. Again, 420 could also undergo a Grob type fragmentation to yield 418 directly. 

The extraordinary polycyclic tetraketone staurone 36 was made6 from 37. The 1,2-diCO relationship in 37 is an ideal candidate for reconnection in this style. 

On treatment with acetic anhydride in pyridine, the yellow tetraketone (68), the yellow triketone (66), and the diketone (67) afforded monoacetyl, diacetyl, and triacetyl derivatives, respectively. All these derivatives contained a tertiary acetoxyl group. However, comparisons of 1H-NMR spectra of the parent ketones with those of the acetyl derivatives indicated that a rearrangement of the molecule or a major conformational change must have occurred. On the basis of extensive H-NMR spectral analysis, structure 69 was proposed for the diacetyl derivative which was derived from the triketone 66. Structure 69 was justified on the basis of conformational arguments. 

The tetraketones (11) gave the benzodiazepines (12), which did not react with a further molecular equivalent of o-phenylenediamine to form bis(benzodiazepines) (58JCS4094) (Scheme 7). 

Oxidation of anopterine with chromic acid-pyridine followed by hydrolysis afforded (85). Oxidation of anopterine with Jones reagent, followed by hydrolysis, was shown to yield a monoketone, which was assigned probable structure (86). Reduction of (86) with sodium borohydride gave a 4 1 mixture, with anopteryl alcohol as the major product. Jones oxidation of anopteryl alcohol gave a mixture of (87) and (88). On oxidation of (85) (from anopterine) with Jones reagent, the tetraketone (89) was obtained. 

Reductive cleavage and hydrolysis of appropriate diisoxazolylmethanes leads to 1,3,5,7-tetraketones, which can be used in the biomimetic synthesis of benzenoid compounds, which are formed in nature by the polyketide pathway. Some of these results are summarized in Table VIII. The synthesis of compounds such as (97) has provided a synthetic equivalent of a 1,3,5,7,9-... 

The possible number of inherently chiral structures and conformers further increases if the calixarene contains both different phenolic units and different bridges in the macrocyclic skeleton. For example, two chiral monoethers 88a,b are available from dihomooxacalix[4]arenes (one -CH2-0-CH2- bridge instead of -CH2-).17188b is the preferred product of the mono-O-alkylation, since the negative charge of the respective phenoxide anion is better stabilized by intramolecular hydrogen bonds due to the smaller distance between the phenoxide anion and the hydroxy groups. Tetraketone derivatives (Y = CH,-C(0)-R) in the two possible partial cone conformations, have been prepared in moderate yields. 

No diacylated selenophene can be obtained by direct acylation however, 2,5-diacyl-3,4-dihydroxyselenophenes (3) were obtained from 1,3,4,6-tetraketones and selenium dioxide in dioxane.69... 

---