نتایج جستجو برای: olefin
تعداد نتایج: 2960 فیلتر نتایج به سال:
207 Novel olefin-linked biscylopentadienylligands have been prepared by McMurry coupling reactions of benzoyland acetyl-cyclopentadienyl sodium. Reactions of the disodium salts with TiC1 4 or TiCl 3 • 3THF afford the alkene-bridged ansa-titanocene dichlorides. 13C-NMR shifts of the bridge carbon atoms do not indicate any interaction between the olefin 'IT-system and the metal.
An efficient acid induced rearrangement of a tetrahalo-7,7-dimethoxybicyclo[2.2.1]heptenyl system leading to substituted indenones is reported. This domino reaction involves dehydration, olefin isomerization, ketal hydrolysis, [3,3]-sigmatropic rearrangement and dehydrohalogenation. The resultant vicinal dihalo olefin moiety in the efficiently generated indenone derivatives was utilized to tran...
The design and development of an extraordinarily interesting new class of chiral sulfur-olefin hybrid ligands with remarkable structural simplicity were described. These unique sulfinamide-olefin ligands have been proved to be highly effective ligands in rhodium-catalyzed asymmetric 1,4-addition reactions of aryl boronic acids to α,β-unsaturated carbonyl compounds (up to 99% yield and 98% ee).
The enantioselective α-vinylation of aldehydes using vinyl iodonium triflate salts has been accomplished via the synergistic combination of copper and chiral amine catalysis. These mild catalytic conditions provide a direct route for the enantioselective construction of enolizable α-formyl vinylic stereocenters without racemization or olefin transposition. These high-value coupling adducts are ...
An iron-catalyzed enantioselective and diastereoselective intramolecular olefin aminochlorination reaction is reported (ee up to 92%, dr up to 15 : 1). In this reaction, a functionalized hydroxylamine and chloride ion are utilized as nitrogen and chlorine sources, respectively. This new method tolerates a range of synthetically valuable internal olefins that are all incompatible with existing a...
We report the development of ruthenium-based metathesis catalysts with chelating N-heterocyclic carbene (NHC) ligands that catalyze highly Z-selective olefin metathesis. A very simple and convenient procedure for the synthesis of such catalysts has been developed. Intramolecular C-H bond activation of the NHC ligand, promoted by anion ligand substitution, forms the appropriate chelate for stere...
An efficient rhodium/olefin-sulfoxide catalyzed asymmetric conjugate addition of organoboronic acids to a variety of nitroalkenes has been developed, where 2-methoxy-1-naphthyl sulfinyl functionalized olefin ligands have shown to be highly effective and are applicable to a broad scope of aryl, alkyl, and heteroaryl nitroalkenes.
the catalytic cracking of a fuel oil over fluid catalytic cracking (fcc) catalyst has been investigated applying different additives. catalyst mixtures consisting of a equilibrium fcc catalyst (e-cat) blended with zsm-5, mcm-41 and mordenite additives were examined at the additive levels of 25 wt.%. the catalytic performance of the matrix was studied in a fixed bed micro-activity test unit (mat...
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