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Showing 1 to 20 of 20 for “"Cyclopropanes"”.
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Mechanistic Studies of Donor-Acceptor Cyclopropanes
… been investigated as a source of donor-acceptor cyclopropanes, providing an understanding of the mechanism of reaction between these cyclopropanes and nitrosoarenes, as well as azo dicarboxylates. Cross-over experiments have been utilized to provide key pieces of experimental evidence that help …
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Design and synthesis of substituted cyclopropanes as conformationally restrained dipeptide mimics
Molecular recognition plays a vital role in a wide variety of biochemical transformations. Of particular interest to chemists, biochemists, and biologists is the process by which enzymes recognize and bind substrates in the catalytic process. The relationship of peptide structure to properties and …
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Synthesis of Novel Cyclobutane Nucleoside Analogues
… rather, the products are suspected to be cyclopropanes from decarbonylation of the ketones, since these are less polar and show shielding of protons in their corresponding NMR spectra, consistent with substituted cyclopropanes.
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Anion Relay Cyclopropanation and Aryl Vinyl Cyclopropane Cope Rearrangements
… to effect anion relay in the synthesis of vinyl cyclopropanes, and subsequent aromatic Cope rearrangement of those vinyl cyclopropanes. This protocol provides a supplementary method of anion relay utilizing readily accessible nucleophiles, which obviates the need for synthesis of alkyl silanes or …
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Silenes: Novel Reagents for Organic Synthesis
… to form silacyclobutanes and silyl-substituted cyclopropanes in moderate yields. Upon silicon-carbon bond oxidation the cyclopropanes were converted directly to 1,4-dicarbonyl compounds, thus demonstrating the formal acyl anion chemistry of acylpolysilanes. In an alternative approach towards …
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Novel syntheses by directed lithiations of N-Boc benzylamines and cyclopropylamines
… $\alpha$ and $\beta$ lithiation-substitution of cyclopropanes. Extension of this chemistry to syntheses of highly functionalized cyclopentane by (3 + 2) cycloaddition and asymmetric synthesis of N-Boc azabicyclic (3.10) hexane was investigated.
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The generation and reactivity of functionalised organozinc carbenoids for cyclopropane synthesis
… for preparation of heteroatom-functionalised cyclopropanes is presented, including [2+1] cycloaddition reactions using a carbene or carbenoid as a cyclopropanating agent with an alkene, ionic stepwise methods, and chemical modifications from existing cyclopropanes. The remainder of this …
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The chemistry of 1,2-dioxines.
… derivitised with a stabilised phosphorus ylide. Cyclopropanes and 2E,4Z-dienoates were prepared in good yield and it was found that the relative ratios of the derivitives could be used to examine the ring-openings. It was found that the selectivity for the cobalt catalysed rearrangement was …
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Stress relief: Exercising Lewis acid catalysis for donor-acceptor cyclopropane ring-opening annulations, a basis for new reaction methodologies
… to assemble diverse polycycles, donor-acceptor cyclopropanes are useful, versatile synthetic equivalents for C-C bond formations. By taking advantage of the strain within these unique, polarized systems, differing molecular architectures can be accessed directly to perform contemporary organic …
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Stereo–Chemical Control of Organic Reactions in the Interlamellar Region of Cation–Exchanged Clay Minerals
… across double bonds to give 3-membered rings (cyclopropanes), insert into OH bonds to give esters and insert into neighbouring C-H bonds to give 4 or 5-membered rings, such as - and -lactams or lactones. Copper salts and complexes were amongst the first catalysts to be used for carbene …
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Synthesis of [beta]-heteroaryl propionates via trapping of carbocations with [pi]-nucleophiles, efforts towards the total synthesis of acutumine, and the design, synthesis, and thermodynamics of protein-ligand interactions at the Src SH2 domain
… affect the thermodynamics of binding. Namely, cyclopropanes were introduced into tetrapeptides to restrict the ligands to their binding conformations. The constricted ligands will then be compared to their appropriate flexible controls via the use of isothermal titration calorimetry (ITC) to …
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Catalyst and substrate effects in enantioselective C–H insertion reactions of α-diazosulfones
… in addition to carbocycles such as fused cyclopropanes. The synthesis of the α-diazosulfones required for subsequent investigations is initially described. Of the twenty seven diazo sulfones described, nineteen are novel and are fully characterised in this work. The discussion is …
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Some uses of tin compounds in organic synthesis.
… the reaction of cS -stannyl alcohols, which give cyclopropanes with inversion. The second piece of work is a regio- and stereo-specific synthesis of allyl stannanes. s-stannyl ester enolates were treated with aldehydes to give alcol products with fairly good stereoselectivity: (~) and (~) enolates …
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ESIMS targeted synthesis of novel {Pt2S2} derivatives
… (E = S, 1a; Se, 1b) and several activated cyclopropanes, N - tosylaziridine, and thiirane with 1a. Epoxides cyclohexene oxide, styrene oxide, epibromohydrin, and 2,2-dimethyloxirane were found to undergo ring-opening when reacted with 1a and derivatives [Pt2(μ-S)(μ-S C6H10OH)(PPh3)4]BPh4 …
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Diverse Applications of Flow Technology in Discovery Chemistry
… series of densely functionalized donor-acceptor cyclopropanes which resulted from the photochemical rearrangement of the bicyclic scaffolds. Expansion of the photochemical screening to a polycyclic iminium ether led to the first example of an aza-di-pi reaction of a charged iminium species. …
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Iridium-catalyzed borylation of aromatic and aliphatic C-H bonds: methodology and mechanism
… of the substrate. Finally, the borylation of cyclopropanes catalyzed by the combination of (η6-mes)IrBpin3 or [Ir(COD)OMe]2 and a phenanthroline derivative is reported in Chapter 6. The borylation occurs selectively at the methylene C-H bonds of the cyclopropane ring over methine or methyl C-H …
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Development of New N-Cyclopropyl Based Electron Transfer Probes for Cytochrome P-450 and Monoamine Oxidase Catalyzed Reactions
… opening pathway. Therefore a new series of spiro cyclopropanes were designed to lock the cyclopropyl group into the appropriate bisected conformation. The electrochemical results reported herein show that the rate constant for ring opening of …
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The Multicomponent Synthesis of Pyrroles from Cylcopropane S Using a One Pot Pd(0) Catalyzed Dehydrocarbonylation Protocol
Previous work done by the Kerr group has shown that tetrahydro-1,2-oxazines can be efficiently synthesized using a three component coupling reaction between a hydroxylamine, aldehyde and cyclopropane diester. This affords the desired heterocycle efficiently with a wide variety of substitution. When …
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SOLID-SUPPORTED PORPHYRINS FOR CATALYSIS AND SENSING
… employed for the homogeneous reactions; cyclopropanes were obtained in 78% yields with selectivity and trans/cis ratio identical to that observed in the presence of catalyst 5. Very interestingly, no catalyst leaching was observed. The reaction scope was investigated using various diazo …