نتایج جستجو برای: supported silyl chromate catalyst
تعداد نتایج: 236684 فیلتر نتایج به سال:
Tetramethylsilane reacts with 2,2,2-trifluoroethanol (TFE) in the presence of a cationic platinum(II) catalyst [(NN)PtMe(TFE)]+ (NN = 1,2-bis(3,5-dimethylphenylimino)butane). Catalytic Si-C bond heterolysis results in the formation of the trimethylsilyl ether, Me3SiOCH2CF3, accompanied by liberation of one equivalent of methane. Preliminary experiments suggest that a rate-determining C-H bond a...
Asymmetric, catalytic reactions of oxocarbenium ions are reported. Simple, chiral urea and thiourea derivatives are shown to catalyze the enantioselective substitution of silyl ketene acetals onto 1-chloroisochromans. A mechanism involving anion binding by the chiral catalyst to generate a reactive oxocarbenium ion is invoked. Catalysts bearing tertiary benzylic amide groups afforded highest en...
An O-Si bond construction protocol employing abundantly available and inexpensive NaOH as the catalyst is described. The method enables the cross-dehydrogenative coupling of an alcohol and hydrosilane to directly generate the corresponding silyl ether under mild conditions and without the production of stoichiometric salt byproducts. The scope of both coupling partners is excellent, positioning...
An anti-Markovnikov selective hydroamination of alkynes with N-silylamines to afford N-silylenamines is reported. The reaction is catalyzed by a bis(amidate)bis(amido)Ti(IV) catalyst and is compatible with a variety of terminal and internal alkynes. Stoichiometric mechanistic studies were also performed. This method easily affords interesting N-silylenamine synthons in good to excellent yields ...
Focusing on the steric and electronic properties of the resonance-stabilized amidine framework, a cationic metal-bisamidine complex was designed as a conjugated combined Lewis-Brønsted acid catalyst. The chiral Zn(II)-bisamidine catalyst prepared from the 2,2'-bipyridyl derived bisamidine ligand, ZnCl₂, and AgSbF₆ promoted asymmetric Mukaiyama aldol reaction of α-ketoester and α,α-disubstituted...
Versatile and base-free copper-catalyzed ?-arylations of aromatic ketones using diaryliodonium salts
A ligand and base-free copper catalyzed synthetic method for the efficient ?-arylation of aromatic ketones is described. In order to avoid strong bases, ketone-derived silyl enol ethers were employed. Their reaction with diaryliodonium salts as aryl source provided intermolecular C–C coupling displaying good functional group tolerance requiring low catalyst loading.
Polymer-supported electrophilic halogenate(I) complexes 2 and 3 promote smooth addition to vinyl and allylsilanes without loss of the silyl group. In conjunction with Amberlyst A26 (OH −-form) vinyl silanes are converted into epoxysilanes.
p2o5-sio2 (30% w/w) was found to be a useful catalyst for the synthesis of various 2-substituted aryl benzimidazoles under solvent-less and in solvent conditions from o-phenylenediamine and aldehydes. the products were directly recrystallized from methanol.
2-(Trimethylsilyl)ethyl 2,2,2-trichloroacetimidate is readily synthesized from 2-trimethylsilylethanol in high yield. This imidate an effective reagent for the formation of 2-trimethylsilylethyl esters without need exogenous promoter or catalyst, as carboxylic acid substrate acidic enough to promote ester additive. A deuterium labeling study indicated that a ?-silyl carbocation intermediate inv...
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