Search results for "hydrosilylation"
showing 10 items of 45 documents
Lewis Base Catalyzed Intramolecular Reduction of Salicylaldehydes by Pinacol-Derived Chlorohydrosilane
2018
Fluorescence of Newo-Carborane Compounds with Different Fluorophores: Can it be Tuned?
2014
Two sets of o-carborane derivatives incorporating fluorene and anthracene fragments as fluorophore groups have been successfully synthesized and characterized, and their photophysical properties studied. The first set, comprising fluorene-containing carboranes 6-9, was prepared by catalyzed hydrosilylation reactions of ethynylfluorene with appropriate carboranylsilanes. The compound 1-[(9,9-dioctyl-fluorene-2-yl)ethynyl]carborane (11) was synthesized by the reaction of 9,9-dioctyl-2-ethynylfluorene and decaborane (B10H14). Furthermore, reactions of the lithium salt of 11 with 1 equivalent of 4-(chloromethyl)styrene or 9-(chloromethyl)anthracene yielded compounds 12 and 13. Members of the se…
Yttrium Hydrido Complexes that Contain a Less “Constrained Geometry” Ligand: Synthesis, Structure, and Efficient Hydrosilylation Catalysis
2001
σ-Bond metathesis of the new linked amino-cyclopentadiene (C5Me4H)CH2SiMe2NHCMe3 with Y(CH2SiMe3)3(THF)2 gave the alkyl-yttrium complex [Y(η5:η1-C5Me4CH2SiMe2NCMe3)(CH2SiMe3)(THF)] (1) in 66% yield. Compound 1 was characterized by NMR spectroscopy and X-ray crystal structure analysis. By hydrogenolysis, 1 was quantitatively converted into the dimeric hydride [Y(η5:η1-C5Me4CH2SiMe2NCMe3)(THF)(μ-H)]2 (2). X-ray crystal structure analysis revealed a Y2H2 core connected to two [Y(η5:η1-C5Me4CH2SiMe2NCMe3)(THF)] fragments in a skewed manner, with a relatively long yttrium−yttrium distance of 3.7085(8) A. In solution, two diastereomers were observed by 1H NMR spectroscopy at −78 °C. Dimer 2 was s…
Electrospray Ionization Mass Spectrometry Studies on the Mechanism of Hydrosilylation of Terminal Alkynes Using an N-Heterocyclic Carbene Complex of …
2006
A new pyridine-4,5-dichloroimidazol-2-ylidene complex of Ir(I) has been obtained, and its catalytic activity toward hydrosilylation of phenylacetylene and 4-aminophenylacetylene has been studied. T...
Various types of polysiloxanes studied by positron annihilation lifetime spectroscopy
2014
Abstract In the work, linear poly(vinylsiloxanes) with regular distributions of vinyl groups along chains, the networks obtained by their hydrosilylation with various hydrogensiloxanes, products of pyrolysis of such networks as well as the networks prepared via reaction of low-molecular siloxanes have been studied by positron anihilation lifetime spectroscopy (PALS). Based on free volume sizes determined by this method, relations between cross-link densities in the investigated systems have been established. They have been compared with the results of swelling experiments conducted in the work and to efficiency of cross-linking reaction evaluated in our previous FTIR investigations of the s…
Hydrogen: a good partner for rhodium-catalyzed hydrosilylation
2014
The influence of hydrogen pressure on the hydrosilylation of ketones catalyzed by [((S)-SYNPHOS)Rh(nbd)]OTf has been studied. We have notably demonstrated that hydrogen significantly affected the outcome of the reaction while not being consumed as stoichiometric reducing agent. In THF, diethyl ether or toluene, the hydrogen pressure exceedingly accelerated the hydrosilylation reaction and preserved or even improved the enantioselectivity of the process. In CH2Cl2, the rhodium catalyst also showed generally higher catalytic activity under hydrogen pressure. Most serendipitously, several ketones were found to give products of absolute opposite configuration upon performing the hydrosilylation…
Deoxygenative Divergent Synthesis : En Route to Quinic Acid Chirons
2020
The installation of vicinal mesylate and silyl ether groups in a quinic acid derivative generates a system prone for stereoselective borane-catalyzed hydrosilylation through a siloxonium intermediate. The diversification of the reaction conditions allowed the construction of different defunctionalized fragments foreseen as useful synthetic fragments. The selectivity of the hydrosilylation was rationalized on the basis of deuteration experiments and computational studies. peerReviewed
Stereoselective Hydrosilylation of Enals and Enones Catalysed by Palladium Nanoparticles
2011
A highly versatile and efficient hydrosilylation method by palladium nanoparticle catalysis allows the direct and chemoselective synthesis of 1) enolsilanes of high isomeric purity, 2) saturated aldehydes or ketones, or 3) the corresponding saturated acetals from α,β-unsaturated aldehydes or ketones. The choice of the product is determined by simply switching the solvent from THF to mixtures of THF/water or THF/alcohol.
A versatile methodology for the controlled synthesis of photoluminescent high-boron-content dendrimers.
2013
Fluorescent star-shaped mol- ecules and dendrimers with a 1,3,5-tri- phenylbenzene moiety as the core and 3 or 9 carborane derivatives at the pe- riphery, have been prepared in very good yields by following different ap- proaches. One procedure relies on the nucleophilic substitution of Br groups in 1,3,5-tris(4-(3-bromopropoxy)phe- nyl)benzene with the monolithium salts of methyl and phenyl-o-carborane. The second method is the hydrosilylation reactions on the peripheral allyl ether functions of 1,3,5-tris(4-allyloxy-phe- nyl)benzene and 1,3,5-tris(4-(3,4,5-tris- AAA with suitable carboranyl-silanes to produce different generations of dendrimers decorated with carboranyl fragments. This ap…
Synthesis, reactivity, crystal structures and catalytic activity of new chelating bisimidazolium-carbene complexes of Rh
2003
A series of new bridging, chelating and pincer N-heterocyclic carbenes of RhI and RhIII have been obtained under mild conditions. The compounds have been fully characterised and their crystal structures determined. The chelate-pincer coordination of the ligands means that the stability of these compounds is significantly greater than other carbene complexes of Rh. The compounds have been tested in catalytic reactions such as hydrogen transfer from alcohols to ketones, and hydrosilylation of terminal olefins and alkynes; they show a high activity for both processes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)