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Showing 1 to 20 of 124 for “"Silyl"”.
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Silyl-mediated and oxidative synthesis of sulfines
Contains fulltext : 19347_silyanoxs.pdf (Publisher’s version ) (Open Access)
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SYNTHESES AND METAL MEDIATED REACTION CHEMISTRY OF 2-SILYL-1,3-DIENES
Asymmetric carbon-carbon bond forming processes and catalytic one-pot reactions remain challenges in organic synthesis. Since the discovery of the Diels-Alder reaction over eighty years ago, it has been one of the most important tools for synthetic organic chemists to synthesize as many as three …
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Studies on the use of alpha-silyl substituted carbanions in organic synthesis
… reaction was studied using o(-trimethylsilylbenzyl carbanion and a series of N-aliphatic/aromatic azomethines. All reactions led stereoselectively to trans-olefins in moderate to low yields. The Peterson intermediate was isolated when neopentylideneaniline was used at room temperature. …
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Lewis Base Activation of Lewis Acids in Asymmetric Aldol Reactions of Silyl Ketene Acetals
… catalyzed/SiCl 4 promoted aldol reaction of silyl ketene acetals and silyl dienol ethers with aldehydes. The weakly acidic species, silicon tetrachloride (SiCl 4), is activated by binding of a strongly Lewis basic chiral phosphoramide, leading to in situ formation of a chiral silyl cation. …
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Synthesis, study and application of silyl ketene imines in Lewis base catalyzed carbonyl addition
… selective catalyst system for the addition of silylated nucleophiles to carbonyl compounds. In general, aldolate-type products containing secondary and tertiary stereogenic centers are obtained in high yield and with excellent stereoselectivities. Despite the breadth of reactivity that has been …
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Lewis Base Catalyzed Aldol Additions of Chiral Silyl Enol Ethers and Total Synthesis of Rk-397
… aldol additions was examined using chiral silyl enol ethers derived from hydroxyisobutyrate and hydroxybutyrate. Trichlorosilyl enolates derived from the chiral methyl and ethyl ketones were subjected to the Lewis base catalyzed conditions, and the intrinsic selectivity of these enolates …
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Studies in Asymmetric Catalysis: Lewis Base Catalyzed, Enantioselective Addition of Trimethylsilyl Cyanide, Trimethylsilyltrifluoromethane, and Glycolate-Derived Silyl Ketene Acetals to Aldehydes
… effective for the addition of glycolate-derived silyl ketene acetals to aldehydes. The sense of diastereoselectivty could be modulated by changing the size of the substituents on the silyl ketene acetals. In general, the trimethylsilyl ketene acetals derived from methyl glycolates with a large …
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Diastereoselective Lithiation-Substitution of N-Silyl-Protected-(S)-Tetrahydro-1H-pyrrolo[1,2-c]imidazole-3(2H)-ones and Applications of Their Derivatives
… imidazolone protected with an N-triethylsilyl group that undergoes diastereoselective lithiation followed by electrophile quench to give C5-substituted products with syn stereochemistry. The N-silylated derivatives may be more easily N-deprotected as compared to previous N-t-Bu analogues …
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Diastereoselective Lithiation-Substitution of N-Silyl-Protected-(S)-Tetrahydro-1H-pyrrolo[1,2-c]imidazole-3(2H)-ones and Applications of Their Derivatives
… imidazolone protected with an N-triethylsilyl group that undergoes diastereoselective lithiation followed by electrophile quench to give C5-substituted products with syn stereochemistry. The N-silylated derivatives may be more easily N-deprotected as compared to previous N-t-Bu analogues …
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Palladium-Catalyzed Cross -Coupling Reactions of Organosilanolates: Methods Development and Application in the Total Synthesis of (+)-Papulacandin D
Finally, an E,Z-1,4-bissilylbutadiene reagent was prepared for the synthesis of unsymmetrical, highly conjugated systems. Two distinct silyl substituents were differentiated in the cross-coupling reaction through the initial use of base-promoted reaction conditions where only one silyl group was …
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Asymmetric synthesis involving silicon
… types of optically active, synthetically useful, silylated diols (17 pairs) have been prepared by asymmetric dihydroxylation of the corresponding allyl and vinylsilanes using Sharpless catalysts. Chiral analysis of these silyl diols was carried out by <sup>1</sup>H NMR methods in the presence of …
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SYNTHESIS AND DEVELOPMENT OF SILICON ANALOG OF FLUORESCEIN FLUOROPHORES AND ESTERIFICATION CATALYSTS
… of a novel silicon analog of fluorescein (silyl fluorescein) was studied in detail. The photo-physical properties and toxicity studies of these fluorophores are also discussed. Compared to fluorescein, silyl fluorescein displayed a 90 nm longer wavelength in its absorption and emission. …
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Selective Gamma Substitution of Alpha-Trimethylsilyl-Beta,gamma-Unsaturated Esters
… were investigated in order to synthesize (alpha)-silyl-(beta),(gamma)-unsaturated esters. Although a nickel-catalyzed coupling reaction of vinyl bromides with lithium ethyl (alpha)-trimethylsilylacetate was employed to synthesize those esters utilized in subsequent reactions, an alternative …
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Asymmetric Lewis base catalysis: I. Lewis base catalyzed halogenation and development of an enantioselective bromocycloetherification reaction; II. enantioselective addition of silyl ketene imines to carbonyl electrophiles
Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2012-06-15T13:39:00Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 2 Thesis-6-12.docx: 11084823 bytes, checksum: 0609048b408ae3adf1f485e3a9dde5d3 (MD5) Burk_Matthew.pdf: 14255171 bytes, …
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Synthese und Charakterisierung von mono- und 1,1´-di-substituierten Ferrocenen sowie [3]- und [4]Ferrocenophanen und ihre 57Fe-NMR-spektroskopische Untersuchung
… Röntgenstrukturanalyse bestimmt werden. I. Monosilyl- und 1,1´-disilyl-substituierte Ferrocen-derivate mit sperrigen Substituenten am Siliciumatom Monosilyl-substituierte Ferrocene und 1,1´-Bis[chloro(dimethyl)silyl]ferrocen lassen sich ausgehend von Monolithioferrocen bzw. Dilithioferrocen …
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Scope and stereochemistry of carbon-carbon bond formation via addition of carbon nucleophiles to nitrones
… nucleophilic addition of Grignard reagents and silyl ketene acetals to acyclic and cyclic nitrones have been studied. A 4:1 selectivity favoring axial addition was observed in the reactions of cis-3,5-dimethyl-2,3,4,5-tetrahydropyridine N-oxide with both methyl and phenyl Grignard reagents and …
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TRANSITION METAL MEDIATED, STEREOSELECTIVE HIGHER-ORDER [6+4] AND DIELS-ALDER [4+2] CYCLOADDITION REACTIONS: SYNTHESIS OF NOVEL 2-SILYL SUBSTITUTED-1,3-DIENYL COMPOUNDS AND THEIR DOMINO REACTIONS
We have prepared various substituted cobaloxime dienes and studied extensively their reactivities in Diels-Alder reactions. Based on the studies with cobaloxime chemistry, we concluded that increased exo selectivities were possible with the insertion of the transition metals in the 2-position of …
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