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Titanocene compounds

Broene and Buchwald37 synthesized chiral titanocene compound 22 for the asymmetric hydrogenation of trisubstituted olefins. [Pg.346]

The polymerization activities of bis-cyclopentadienyl titanium compounds are lower than those of bridged bis-cyclopentadienyl titanium compounds. Miya-shita et al. reported the polymerization activities of several bridged bis-cyclopentadienyl titanium compounds [15]. They found that the catalytic activity of CH2(Cp)2TiCl2 is the highest among bis-cyclopentadienyl titanocene compounds. The data indicate that the polymerization activities and also syndiospecificity increase with a decreasing angle between the Cp centroid-Ti-Cp centroid in bis-cyclopentadienyl titanocene compounds. [Pg.367]

The parent titanocene compound of stoichiometry TiCioHio and its related derivatives exhibit a complex chemistry involving dimers. Structural studies of ligand-bridged... [Pg.114]

Several a-C titanocene compounds can be prepared by Mg reduction of dihalo complexes containing cj-alkenyl-and cj-alkenyl-dimethylsilyl-Cp substituents (Section 4.05.4.1.3.(ii)). [Pg.547]

The absorbance at 814 cm" includes all three of the titanocene compounds. Stand-alone peaks for TiDi, monomethylmonochloro titanocene, or DMT were not observed however, the chemo-metrics package in the Quant-IR program was successfully used to extract concentration information for each component. H NMR data and the IR spectra were used to construct a calibration curve... [Pg.356]

Upon irradiation, the titanocene compounds presumable break up into diradicals This was illustrated as follows... [Pg.78]

Recently, titanocene compounds such as Cp2TiCl2 [30a,30b], titanium compounds coordinated with similar cyclopentadienyl ring [30m-30o] and tetrahedral organotitanium compounds [30p-31] have been reported. [Pg.236]

Compound 45 was obtained from the addition of Bu (C = C)3Bu to activated permethyltitanocene and has been derivatized by simple means, e.g. hydrogen chloride, bromine or dihydrogen. These reactions yielded the practically useful functionalized titanocene compounds containing a chiral auxiliary ligand with an intramolecularly coordinated or a free double bond 46. The compounds have been characterized by spectroscopic means and X-ray crystallography. Reduction of [Cp2 MCl2] (M = Ti, Zr) with Mg in the presence of disubstituted... [Pg.204]

The hydroalumination of terminal alkenes by LiAlH4 catalyzed by titanocene and zirconocene dichloride, CpjTiCh and CpjZrCh, respectively, has been reported by Isagawa [16] and Sato [14]. Again, the titartium compound proved to be more active... [Pg.49]

A rather new concept in the context of domino radical cydizations has been developed by Gansauer and coworkers utilizing titanocene-complexes for the radical opening of unsaturated epoxides. The titanocene-catalyzed reactions [61] of 3-145 primarily led to radical 3-146, which underwent a subsequent intermolecular addition to a present a,(3-unsaturated carbonyl compound to form bicyclic carbocy-cles of type 3-148 via the intermediate 3-147 after aqueous work-up (Scheme 3.38) [62]. From a kinetic point of view, the reaction is remarkable since the intermolecular addition of simple radicals to a,(3-unsaturated carbonyl compounds is not an easy task, as highlighted above. [Pg.244]

Recently, the Cuerva group also presented a titanocene-catalyzed domino cycliza-tion of an aryl epoxypolyene such as 3-151, which led to the formation of a trans/ anti/trans-fused tricyclic compound 3-152, though in only moderate yield. Nevertheless, six stereogenic centers are formed in this domino process [64]. 3-152 could be transformed into the natural terpenoid stypoldione (3-153) (Scheme 3.40) [65]. [Pg.246]

The nature of the substituent directly attached to the N-atom influences the properties (basicity, reduction potential, etc.) of the C = N function more than the substituents at the carbon atom. For example, it was found that Ir-dipho-sphine catalysts that are very active for N-aryl imines are deactivated rapidly when applied for aliphatic imines [7], or that titanocene-based catalysts are active only for N-alkyl imines but not for N-aryl imines [8, 20, 21]. Oximes and other C = N-X compounds show even more pronounced differences in reactivity. [Pg.1194]

The (3-metaloxy radical was first exploited for synthetic purposes in C—H and C—C bond-forming reactions by Nugent and RajanBabu through the use of titanocene(III) chloride as an electron-transfer reagent [5]. They established that the (3-titaniumoxy radicals formed after electron transfer can be reduced by hydrogen atom donors, e. g. 1,4-cy-clohexadiene or tert-butyl thiol, that they add to a,(3-unsaturated carbonyl compounds, and that they can react intramolecularly with olefins in 5-exo cyclizations. [Pg.436]

More recently, Doris et al. have described the reductive ring-opening of a-keto epoxides [16]. In this manner, p-hydroxy ketones can be obtained in high yields. The synthesis of enantiomerically pure compounds can easily be realized. The titanocene] 111) reagents are distinctly superior to samarium diiodide, which is also known to induce this transformation. [Pg.437]


See other pages where Titanocene compounds is mentioned: [Pg.829]    [Pg.15]    [Pg.259]    [Pg.450]    [Pg.181]    [Pg.447]    [Pg.267]    [Pg.114]    [Pg.130]    [Pg.132]    [Pg.829]    [Pg.15]    [Pg.259]    [Pg.450]    [Pg.181]    [Pg.447]    [Pg.267]    [Pg.114]    [Pg.130]    [Pg.132]    [Pg.154]    [Pg.158]    [Pg.157]    [Pg.127]    [Pg.158]    [Pg.185]    [Pg.38]    [Pg.155]    [Pg.105]    [Pg.55]    [Pg.517]    [Pg.530]    [Pg.104]    [Pg.564]    [Pg.565]    [Pg.355]    [Pg.363]    [Pg.364]    [Pg.365]    [Pg.370]    [Pg.379]    [Pg.383]    [Pg.390]   


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