Diketone group

APG, p-azidophcnyl glyoxal, is a heterobifunctional crosslinker containing an arginine-specific diketone group on one end and a photosensitive phenyl azide group on the other end (Thermo... 

The final steps in a total synthesis of (+ )-gloeosporone (3, a natural germination inhibitor of a fungus) required oxidation of the acetylene group of 1 to a diketone group. The oxidation was carried out in 74% yield by the catalytic Ru02 procedure of Sharpless. On liberation (pyridine-HF) of the C7-hydroxyl group, the hydroxy... 

We note here that Cjl —CO copolymer, which supposedly contains small amounts of C2H4. incorporated in a transverse fashion to generate 1,3-diketone groups, has been made using Co2(CO)8 as catalyst42 . This copolymer contains 18 mol% CO and is therefore not alternating, unlike the copolymers formed using Pd and Ni compounds as catalysts. 

When a competition between an amido group and a potentially more reactive group is possible, chemoselectivity is observed, so that amino or /3-diketone groups are selectively N- or C-arylated, respectively (Equation (95)). 

Thus acetylacetonates of Zn, Ni, and Mn are trinuclear, Fig. 11-4, while Co(acac)2 is tetranuclear all have bridging j8-diketonate groups. The presence of bulky substituents on the j8-diketones such as Me3C sterically impedes oligomerization and monomers are formed. However, these are commonly solvated by H20, ROH, or py to give 5- or 6-coordinate complexes, trara-M(dike)2Ll 2. 

Complexes with the composition M(dike)2 usually exist as oligomers, so that the metal atoms are coordinatively saturated. For example, the acetylacetonate complexes of Ni, Zn, and Mn exist in the solid state as trimers of varying stracture, with bridging /3-diketonate groups (20). The extent of oligomerization varies with the metal cation forms a... 

The preparation of polymer bound Ni-chelates (54) of the acac type started from chloromethylated polystyrene and pentane-2,4-dione leading with catalytic amounts of sodium ethoxide to the polymer diketone (53) (Eq. 21) Seven % of pendent diketone groups of soluble linear (55) were converted with 1,2-diamtnoethane and Ni(II) to the polymer Sdiifr base chelate (54). In the reaction of (55) to (54) two pendent diketon must react. But surprisingly no network formation was reported. 

At pH 6.5-S.5 the enol form of dibenzoylmethane (formula 54.1), a reagent of the P-diketone group, forms a yellow uranyl chelate complex which has been used for determination of uranium [76,77]. It dissolves in aqueous ethanol medium containing pyridine, or may be extracted with ethyl acetate, butyl acetate, or CHCI3 [78]. 

Many of the therapeutic effects of curcumin are attributed to its strong antioxidant property. Most natural antioxidative compounds can be classified into two types phenolic compounds and 3-diketone compounds [17]. Sesaminol from sesame belongs to the former type, and n-tritriacontan-16,18-dione from the leaf wax of Eucalyptus belongs to the latter type. However, few antioxidative substances possess both phenolic hydroxy and /3-diketone groups in one molecule, and curcumin has both features. 

In a subsequent paper, Cowie et al. (1986 b) reported on the formation of interesting and unexpected products obtained from this chelate complex 10.52. When the latter was refluxed in toluene, dediazoniation and ortho metalation of one of the phosphine groups took place leading to the yff-diketonate complex shown in Fig. 10-1. The diketonate group chelates through both O-atoms and is formed by hydride transfer from the metal to the carbene C-atom that is generated by the dediazoniation. 

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