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Titanium complexes 1,3-diketones

As in the case of the related titanium complexes, the oxidation of the unshielded silyl enolates affords the related 1,4-diketones (Table 6). [Pg.497]

The reaction of diketone with aldehydes in the presence of a stoichiometric amount of a titanium complex, prepared from the tridentate ligands and Ti(O Pr)4, provided 5-hydroxy-p-ketone esters in good yield and high optical purity [118] (Scheme 14.41). [Pg.217]

Organometallic complexes based on cyclopentadienyl and exemplified by [TiCl2Cp2] and also [FeCp2] also present a different spectrum of activity compared to cisplatin. Again, DNA synthesis is selectively inhibited but the exact mechanism is unclear. The titanium j8-diketonate, budotitane, is another Ti complex with antitumour activity. [Pg.163]

In order to obtain high selectivities in the reduction of linear carbonyl compounds, very often chelating reagents are added to fix the substrate in a specific conformation. Titanium complexes are known to be versatile reagents in such a reduction process, especially with dicarbonyl compounds [41]. Thus, the stereoinduction in the reduction of diketones alternates with the distance of the two carbonyl groups from each other [42]. The 1,2-induction in the reduction of diacetyl or benzil 91 is independent of the addition of titanium tetrachloride and predominantly yields the meso products 92 (displayed in Scheme 3.20). [Pg.156]

Strontium titanate (SrXi03) by reacting titanium isopropoxide and a strontium beta-diketonate complex at 600-850°C and 5 Xorr. [Pg.99]

Strontium titanate (SrTi03) has a large dielectric constant of 12, and a high refractive index with potential opto-electronic applications. It is deposited by MOCVD from titanium isopropoxide and a strontium beta-diketonate complex at 600-850°C and 5 Torr.t" " ... [Pg.315]

The addition of trimethylsilyl (TMS) cyanide to aldehydes produces TMS-protected cyanohydrins. In a recent investigation a titanium salen-type catalyst has been employed to catalyse trimethylsilylcyanide addition to benzaldehyde at ambient temperature1118]. Several other protocols have been published which also lead to optically active products. One of the more successful has been described by Abiko et al. employing a yttrium complex derived from the chiral 1,3-diketone (41)[119] as the catalyst, while Shibasaki has used BINOL, modified so as to incorporate Lewis base units adjacent to the phenol moieties, as the chiral complexing agent11201. [Pg.29]

TV-phenylbenzohydroxamic acid, 506, phthalocyanines, 865 polypyrazolylborates, 248 porphyrins, 823 pseudohalides, 228 Titanium(III) complexes octaethylporphyrin reaction with dioxygen, 325 Titanium(IV) complexes 1,3-diketones, 376 triazines... [Pg.1101]

The reactivity profiles of the boronate complexes are also diverse.43 For example, the lithium methyl-trialkylboronates (75) are inert, but the more reactive copper(I) methyltrialkylboronates (76) afford conjugate adducts with acrylonitrile and ethyl acrylate (Scheme 16).44 In contrast, the lithium alkynylboronates (77) are alkylated by powerful acceptors, such as alkylideneacetoacetates, alkylidene-malonates and a-nitroethylene, to afford the intermediate vinylboranes (78) to (80), which on oxidation (peracids) or protonolysis yield the corresponding ketones or alkenes, respectively (Scheme 17).45a Similarly, titanium tetrachloride-catalyzed alkynylboronate (77) additions to methyl vinyl ketone afford 1,5-diketones (81).4Sb Mechanistically, the alkynylboronate additions proceed by initial 3-attack of the electrophile and simultaneous alkyl migration from boron to the a-carbon. [Pg.148]

A transition metal complex consisting of titanium tetrachloride and jS-diketone cyclophane where n = 10 has been prepared and is described (2). [Pg.391]

A large number of bidentate and chelated titanium(IV) complexes have been prepared. By far, the greatest number of reports concern the jS-diketonate complexes, which provide an extensive series of types TiXsL, TiX4(LH), TLX2L2, [TiL3]+, TiOXL, and [TiOL]2 (L = /3-diketonate, LH = /3-diketone). ... [Pg.4908]

Some crystal structures of chelate complexes have been reported. An O-acryloyl-lactate-TiCU complex (Fig. 3) [26,27] has rare out-of-plane (Fig. 4) coordination of the acryloyl carbonyl group to the titanium a further study has been conducted [28]. Diethyl phthalate-TiCU [29], l,2-diketone-TiCl4 [25], and achiral [24] or chiral [30] acyloxazolidinone-TiCU complexes have been reported to involve in-plane coordination as shown in Fig. 5. The /S-alkoxyketone-TiCU complex shown in Fig. 6 [31] is characterized by a rare out-of-plane coordination geometry (dihedral bond angle of... [Pg.654]

The diastereoselectivity of reduction of a series of symmetrical diketones to the corresponding diols revealed an intriguing dependance on the separation of the carbonyl groups, but the selectivity was not generally useful. However, in the case of 1,3-diketone (71) lithium borohydride alone produced the anti isomer (70) with 91% diastereoselectivity, but prior addition of titanium tetrachloride gave the syn-diol (72) with 96% diastereoselectivity via a chelated intermediate analogous to the crystalline complex between the diketone and TiCU (Scheme 11). ... [Pg.13]

Mixed-ligand precursors are also frequently employed in CSD processing. For example, titanium tetraisopropoxide, which is too reactive to be directly employed in most CSD routes, may be converted into a more suitable precursor by a reaction with either acetic acid or acetylacetone (Hacac). Such reactions are critical in dictating precursor characteristics and have been studied extensively. - Using these reactions, crystalline compounds of known stoichiometry and structure have been synthesized that may subsequently be used as known precursors for film fabrication.Mixed-hgand molecules (carboxylate-alkoxide and diketonate-alkoxide ) represent complexes that are not easily hydrolyzed. A typical structure for one of these compounds is shown in Figure 27.3e. [Pg.534]

The reactions of Cp2TiCl2 with 2,6-diacetylpyridine-bis(S-alkylisothiosemicarbazones) give bis-Cp complexes with isothiosemicarbazone ligands coordinated to the titanium atom which contain terminal free amino groups. Reactions of these derivatives with /3-diketones have been carried out to afford cyclic complexes.1584... [Pg.596]


See other pages where Titanium complexes 1,3-diketones is mentioned: [Pg.376]    [Pg.1798]    [Pg.1022]    [Pg.66]    [Pg.394]    [Pg.196]    [Pg.138]    [Pg.968]    [Pg.829]    [Pg.336]    [Pg.170]    [Pg.22]    [Pg.138]    [Pg.701]    [Pg.4908]    [Pg.5273]    [Pg.5274]    [Pg.90]    [Pg.38]    [Pg.186]    [Pg.187]    [Pg.716]    [Pg.346]    [Pg.968]    [Pg.969]    [Pg.4907]    [Pg.5272]    [Pg.5273]    [Pg.1747]    [Pg.10]    [Pg.308]   
See also in sourсe #XX -- [ Pg.2 , Pg.3 , Pg.336 , Pg.376 ]




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