2,4-Pentanedione derivatives

Cobalt(III) l,5-diaIkyl-2,4-pentanedionate derivatives have been obtained by oxidation of C0L2 with hydrogen peroxide in water . Analogously, the vanadium(IV) derivative VO(acac)2 is oxidized by I2 to the polyiodide [VO(acac)2]l5 . Charge ti ansfer complexes of general formula [M(acac) I]l3 (M = Fe , Co , n = 3 M = Ni, n = 2 ) have been isolated and characterized from the reaction of M(acac) with diiodine. 

With dipivaloylmethane, the zinc(II), cobalt(II) (12), and iron(II) complexes (19) are all isomorphous. A three-dimensional x-ray structural determination (12) of the Co(DPM)2 shows a tetrahedral configuration. The copper(II) complex of this ligand and the nickel(II) derivative are planar. The 3-phenyl-2,4-pentanedione derivative of copper(II) also is planar (7). 

The syntheses of acetylacetone (2,4-pentanedione) derivatives of beryllium,18 aluminum,23 zirconium,14 and thorium6 are representative of this general method. 

At about the same time that the potential of the lanthanide chelates for studying carbohydrates was first recognized, another group described experiments with chelates of normal transition metals, such as the 2,4-pentanedione derivatives (6) shown. As the shifts induced by these... 

Condensation of 2,3 4,5-di-O-benzylidene-D-ribose or related aldehydo-D-ribose or -D-glucose derivatives with a number of active methylene compounds, e.g., pentane-2,4-dione, gave the expected Knoevenagel condensation products, which all showed antiviral activity and cytotoxicity the most effective against herpes simplex virus was the ribose-2,4-pentanedione derivative (34) titanium... 

Bromocyclobutanone and o-phenylenediamine condense to give the strained ring system cyclobuta[6]quinoxaline,33 and the cyclopenta[6]-quinoxaline ring system is similarly synthesized from suitable cyclo-pentanedione derivatives.34... 

Another interesting ketyl cyclization is that reported for a 1,5-pentanedione derivative on reaction with magnesium [Eq. (20) 52]. 

As shown in Equations (20) and (21), the pentavalent 1 1 dibenzostiboles-Cl2 adducts (108) and (109) react with diaryllithium reagents and pentanedione derivatives to provide spirocyclic antimony heterocycles. This reactivity extends to nucleophilic addition of chloride which yields hexavalent derivatives of stibolanes and their dibenzo analogues (Equation (22)) <77JOM(i36)i73>. 

Reactions of l-Diazo-2,5-pentanedione Derivatives with Vinyl Ethers Catalyzed by the (4S,5S)-PyBOX-Ph2-Lu(OTf)3... 

The reactions were carried out by adding a solution of l-diazo-2,5-pentanedione derivatives and vinyl ethers to a suspension of Rh2(OAc)4 (2 mol%), MS 4A, (4S,5S)-PyBOX-Ph2-Lu(OTf)3 conqtlex (10mol%), and MeOH (10mol%) over a period of 1 h in dried and purified CH2CI2 at 23 °C. 

The scope of the cyclic carbonyl ylides was extended to those generated from l-diazo-2,5-pentanedione derivatives, which were reacted with butyl or TBS vinyl ether and catalyzed using the (45,55)-PyBOX-4,5-Ph2-Lu(OTf>3 complex to give good levels of asymmetric inductions (75-84% ee) (Table 7.24) [66]. 

Meldrum s acid, pK 7.4, is exceptionally acidic in comparison to an acyclic analog such as dimethyl malonate, pK 15.9. For comparison, 5,5-dimethyl-1,3-cyclohexane-dione is only moderately more acidic than 2,4-pentanedione (11.2 versus 13.43). The pK values are those for DMSO solution. It is also found that the enhanced acidity of Meldrum s acid derivatives decreases as the ring size is increased. Analyze factors that could contribute to the enhanced acidity of Meldrum s acid. 

Tnfluoroacetonitrile oxide also reacts with stabilized enolate ions, such as that derived from 2,4-pentanedione, to give good yields of 1,3-dipolar adducts [38] (equation 38). 

How many different enolates may arise from deprotonation of 2,4-pentanedione Draw Lewis structures for each, and predict which is likely to be the most stable. Check your conclusions by examining the energies of the different possible enolates (enolate A, B...). Is the most stable enolate that derived from deprotonation of the most electron-poor hydrogen Compare the electrostatic potential maps of the anions with each other and with your Lewis structures. Revise your drawings to be consistent with the maps. Why is one of the enolates preferred over the others ... 

Comprehensive work in this field has been done by Slovak authors (98MI1, 95M1359, 96CCC269, 96CCC371, 97CCC99). They prepared 2-substituted (H, Me, Ph) 4-, 5-, 6-, and 7-nitrobenzoxazoles, which were then reduced to amines (not isolated) and subjected to subsequent nucleophilic substitution with activated enol ethers such as alkoxymethylene derivatives of malonic acid esters and nitrile, 3-oxobutanoic acid esters, pentanedione, or cyanoacetic acid esters to yield aminoethylenes 8. 

Alkylation of the cyclization product 115 and the following hydrolysis gave 9-alkyl substituted 6-oxo-6,9-dihydroimidazo[4,5-/i]quinoline-7-carboxylic acid derivatives 119, compounds useful as antibacterials (no data) [80JAP(K)1], 4(7)-Aminobenzimidazole can react with 1,3-diketones as a bidentate nucleophile, but with 2,4-pentanedione in glacial acetic acid it gives a Combes product, l//-6,8-dimethylimidazo[4,5-/i]quinoline 120, accompanied by 4(7)-acetamido-benzimidazole (91T7459). 

Reaction of 6-halopurines with Michael acceptors under Heck conditions gives N- -substituted hypoxanthine derivatives <00CCC797>. Reactions of a series of 1-aminobenzimidazoles and l-amino-3-methylbenzimidazolium chlorides with 2,4-pentanediones afford pyridazino[l,6-a]benzimidazoles and 2-pyrazolylanilines, the product ratio depending on conditions and on the electronic character of the substituents at the benzene moiety <00BMC37>. Cyclization reactions of adenine derivative 75 with different amines or hydrazine afford tricyclic polyaza compounds 76 <00CCC1109>. 

Using optimized conditions (pentanedione 2 equiv., NaHCOs 4 equiv., H2O-THF 2 1, 90°C, 24 h), Ai-acetyl-o-glucosamine (66) gave the gluco- and manno ketones 69a and 70a in a 4 6 ratio and 83% yield, whereas Af-acetyl-o-mannosa-mine (67) led to the same products in a 3 1 ratio and 40% yield. This poor yield has been explained by the instability of 70a in the reaction mixture. These compounds were easily separated by crystallization of their acetylated derivatives 69b and 70b. Applied to A-acetyl-D-galactosamine (68), the same reaction conditions gave the C-glycosidic ketone 71a, isolated as the acetylated compound 71b (Fig. 12, Table 4). 

Another class of pyrrole derivative may be obtained by the interaction of l-amino-l-deoxy-2-ketoses or 2-amino-2-deoxyaldoses with a jQ-dicarbonyl compound. Unlike the previous type (which is N-substituted), these pyrrole derivatives have a tetrahydroxybutyl group in the a- or /8-position with respect to the nitrogen atom of the ring, in addition to other groups arising from the dicarbonyl compound used in the condensation. The formation and reactions of this type of pyrrole derivative have been discussed in detail in two articles in this series48,49 they will, therefore, only be treated briefly. 1-Amino-l-deoxy-D-fructose (53) reacts with 2,4-pentanedione to give50 pyrrole derivative 54a similar pyrroles were obtained with ethyl acetoace-tate,50,51 which yields 54b. 

The organometallic chemistry of the first-row transition metals generally starts with the binary metal carbonyl organometallic complexes. Noncarbonyl organometallic complexes starting with other easily accessible binary compounds provide entries to a broader spectrum of complexes. In this context, we describe the synthesis of the mixed sandwich complex (tj5-pentamethylcyclopentadienyl) ( j5-cyclopentadienyl) iron as an example of the synthetic utility of the solution-stable derivative (>j5-pentamethyl-cyclopentadienyl) (2,4-pentanedionate) iron. 

Moreover, 3-benzoyl-2,4-pentanedione (215) is obtained when benzoylchloride is employed to the acetylacetone derivate i94143) whereas the reaction with benzaldehyde results a mixture of 3-benzylidene-2,4-pentanedione (213) and 3-[a-hydro-xy-benzyl]-2,4-pentanedione (214)143 ... 

Alternatively, a measured volume of air drawn through an impinger containing ammonium acetate and 2,4-pentanedione formaldehyde forms a fluorescence derivative, 3,5-diacetyl-l,4-dihydrolutidine fluorescence of the solution measured by a filter fluorometer (Dong and Dasgupta, 1987). 

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