1.3- Diketone resin

Solid-phase synthesis by reacting polymer-bound fi-keto esters with hydrazine hydrate or monosubstituted hydrazines. Schon et al. (03SL983) (Scheme 17) developed a new 1,3-diketone resin and compared it with /7-keto ester resin 69 as the basis for a selective scavenger for hydrazines and for the selective removal of primary amines in the presence of... 

Claisen condensation Resin 40 (1000 mg, 460 pmol) was suspended in a solution of the requisite carboxylic ester (13.8 mmol, 30 equiv.) in DMA (13.5 mb). Under an inert atmosphere, a 60% dispersion of NaH (180 mg, 4.6 mmol, 10 equiv.) was added and the mixture was well shaken under argon at 80 °C for 1 h. The resulting mixture was filtered, and the resin was washed with 30% (v/v) acetic acid/H20, DMA, DMSO, and iPrOH, and dried in vacuo. A 95 % conversion to the diketone resin 41 was typical. 

The temperature must be carefully regulated, and in no case must it exceed 150°. In this preparation, as well as in the preparation of other ketones by the Nencki reaction, higher temperatures lead to the formation of a highly colored and resinous product which probably contains a little diketone. 

Several combinatorial approaches to the discovery of transition metal based catalysts for olefin polymerization have been described. In one study Brookhart-type polymer-bound Ni- and Pd-(l,2-diimine) complexes were prepared and used in ethylene polymerization (Scheme 3).60,61 A resin-bound diketone was condensed with 48 commercially available aminoarenes having different steric properties. The library was then split into 48 nickel and 48 palladium complexes by reaction with [NiBr2(dme)] and [PdClMe(COD)], respectively, all 96 pre-catalysts being spatially addressable. 

The resin-bound 1,3-oxazinium salt 116, obtained by oxidation of 4//-l,3-oxazines 115 with 2,3-dicyano-5,6-dichloro-p-benzoquinone (DDQ), behaved as /3-diketone equivalents and formed pyrazoles 117 through a functionalizing release process on treatment with hydrazines (Scheme 18). When the hydrazines were substituted (R = Me, Ph), the oxazinium salts reacted selectively to afford one regioisomer 117 <2004JC0846>. 

The kinetics of ligand exchange between [M(dik)4] (M = Zr or Hf dik = acac or tfacac) and the corresponding free /3-diketones have been studied by Adams and Larsen.233 [Zr(acac)4] exchanges ligands with a polystyrene resin functionalized with acetylacetonate groups to give a polymer-bound zirconium complex.234... 

Treatment of l,2,3,4-tetraphenylbut-2-ene-l,4-dione with triethyl phosphite yields tetraphenylfuran (79JOC494), 2,5-Dimethylfuran has been prepared in high yield (94%) by distillation of hexane-2,4-dione from an acidic ion exchange resin. Alkylfurans are important as synthons for 1,4-diketones (73S209). 

Although the structures of a series of 6-substituted 4-methoxypyran-2-ones have been established by chemical means, their alternative formulation as derivatives of 2-methoxy-pyran-4-ones was mainly excluded on the basis of an absorption at 1733 cm-1 attributable to the pyran-2-one system (59JA2427). This report concludes that pyran-2-ones exhibit their first carbonyl band at ca. 1725 cm-1, whereas pyran-4-ones absorb at ca. 1667 cm-1. Similarly, absorption at 1724 cm-1 indicated a pyran-2-one structure for yangonin (98), the major constituent of kava resin, and this has been confirmed by an unambiguous synthesis. Pseudoyangonin (99) absorbs at 1667 cm-1, characteristic of a pyran-4-one (60JCS502). Comparison of the spectra of some constituents of the rosewoods with that of yangonin established them as pyran-2-ones. The products from the reaction of malonyl chloride with some 1,3-diketones were identified in part by IR spectroscopy. 

Morpholinocyclohex-l-ene is smoothly acylated by diketene to give a fused pyranone (61CB486, B-68MI22400). The initially formed diketone ring-closes and the pyranone results from elimination of morpholine. Using the cyclopentanone-derived enamine, much resinous material is formed and the yield of pyranone is reduced. 

Figure 5.10. Double condensation of resin-bound aldehydes with 1,3-diketones [108],...

The polymer-assisted solution-phase (PASP) synthesis of a 192-member group of 1,5-biaryl pyrazoles from 1,3-diketones and 4-hydrazinobenzoic acid as precursors has been reported <2004JC0332>. Condensation of aromatic or aliphatic esters with resin-supported sulfonamides 527, followed by cyclization with hydrazines, activation with trimethylsilyldiazomethane, and cleavage using amines, provided highly substituted, isomeric pyrazoles 528 and 529 (Scheme 63) <20000L2789>. 

Cation Exchange Extractants. This class of extractants includes phenols, branched alkyl carboxylic acids, alkyl phosphoric acids, diketones, and alkyl-aryl sulfonic acids. The last group listed, sulfonic acids, are analogous to sulfonic-acid cation exchange resins and have very little selectivity. Diketones, alkyl phosphoric acids and carboxylic acids can provide both cation exchange functions and coordination functions. This feature has made bis(2-ethylhexyl)phosphoric acid one of the most versatile and powerful extractants of this type. (5) The nation below illustrates simple cation exchange extraction. 

Various m- and p-hydroxychalcones were anchored to a Wang resin through their phenolic groups. Stetter reactions were performed with various aliphatic, aromatic, and heteroaromatic aldehydes, affording 1,4-diketones. m-Chalcones, as well as aliphatic and aromatic aldehydes, gave superior results. 

Various (l-hydroxyallyl)aryl carboxylic acids were attached to a Wang resin and then oxidized. The resulting enones were submitted to a Stetter reaction with aromatic aldehydes, affording 1,4-diketones, which were transformed to the corresponding pyrroles. 

Monoalkylation on polystyrene resin using tetrabutylammonium fluoride (TBAF) (Table 8, entry 12) [454] Resin bearing a 1,3-diketone (20 mg, 8.6 mmol) was treated with a 1 M solution of BU4NF in THF (86 mb) for 2 h at r. t. After the addition of 150 mb of a 2.5 m solution of the appropriate alkylating agent, the reaction was allowed to proceed for a further 2 h. The resin was then filtered off and washed as follows ... 

Alkylation (optional low-yield step) A 1 m solution of TBAF inTHF (4.5 mb, 4.5 mmol, 10 equiv.) was added to the resin-bound diketone 41 (1.08 g, 0.45 mmol) at rt and the mixture was shaken for 1 h and then treated with allyl bromide (779 pb, 9 mmol, 2 equiv.). The resulting mixture was shaken for a further 2 h, then filtered, and the resin was washed vtith CH2CI2, DMA, DMSO, and iPrOH, and then air-dried to yield the resin-bound 42. Only approximately 40 % conversion was observed at this stage. 

When used in PVC organophosphites act as secondary heat stabilizers. In other resins such as PP, PS, HOPE and ABS plastics they function as antioxidants. p-Diketones are well-known co-stabilizers more particularly for zinc carboxylates. The synergistic action of epoxidized fatty acid esters like ESO or butylepoxy stearate as plasticizer, HCl scavenger and stabilizer for labile chlorine atoms in the catalytic presence of Zn and Cd salts is shown in Fig. 7 (see also 5.2.3)... 

Hz) have been isolated, including octahedral Co(R R C=N—NHCOR )X2 (R = H, Me, or C5H10 R = Ph, p-MeOPh, or Me R = Ph, o-HOPh, or p-MeOPh X = NO3, Cl, Br, or SCN) and dimeric five-co-ordinate Co(R R C= NN=C0R )2- Formation constants have been reported for reactions between M bipy (M = Co, Ni, or Cu) and monoanions of the ) -diketonates acac, benzoyl-acetone, dibenzoylmethane and dipivaloylmethane. Cobalt ions have been extracted from an ion exchange resin by formation of Co(tta)2Bn (Htta = 2-thenoyl-trifluoroacetone, B = py base) and the synergistic effect decreased in the order py > > y-pic > a-pic > y-colidine isoquinoline > piperidine > 4-benzoyl-... 

Irradiation of a methanol solution of 5-phenyltropolone (106) was found to give product 107 in addition to resinous products. Since 107 is assumed to arise from the 1,3-diketone 109 by way of formation of the type B cyclization product 108 followed by rearrangement, 106 properly belongs to the class of type B cyclizations. IR data of the resinous photo-... 

Kirschning and coworkers have recently reported the synthesis of a resin-bound diketone for the sequestration of amines and hydrazines [14]. The resin-bound diketone was synthesized via oxidation of a chloromethyl resin, followed by reductive coupling with 2,4-pentadione, to provide the requisite scavenger resin. This resin was found to be more efficient than supported-aldehydes for amine and hydrazine scavenging and, furthermore, found to be selective for the scavenging of primary amines over secondary amines (Scheme 8.10). 

Scheme 8.10 Resin-bound diketones in hydrazine scavenging.

In the peroxide formulation initiation, the organochlorine impurities that are present in commercial BisGMA accelerate the decomposition of the peroxides, a process that forms free radicals and reduces the stability and shelf life of the resin. In the a,b-diketone formulation, the organochlorine impurities complex with other additives in the formulation that are present to enhance free-radical formation. The presence of the impurities thus reduces the photoefficiency and negates the advantages of simple photoinitiated diketone curing. 

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