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Showing 1 to 20 of 56 for “"ring-closing metathesis"”.
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Ligand variation in molybdenum asymmetric ring-closing metathesis catalysts
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2002.
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Highly functionalized piperidines via ring-closing metathesis of dehydroamino acids
Contains fulltext : 126486.pdf (Publisher’s version ) (Open Access)
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Tandem benzannulation-ring closing metathesis strategy for the synthesis of benzo-fused nitrogen heterocycles ;
A tandem benzannulation-ring closing metathesis strategy for the efficient synthesis of benzo-fused nitrogen heterocycles such as dihydroquinolines, benzazepines, and benzazocines has been developed. This strategy is based on the benzannulation reaction of ynamides with cyclobutenones or …
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Chiral molybdenum and tungsten imido alkylidene complexes as catalysts for asymmetric ring-closing metathesis (ARCM)
… of catalysts prepared in Chapter 2 in asymmetric ring-closing metathesis (ARCM) is described. -- Chapter 5. Synthesis, characterization and reactivity of (±)(Me2)W(Neo) and (±)(iPr 2)W(Neo) . PMe2Ph is discussed.
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Asymmetric synthesis of medium-sized carbocycles spirocycles and oxabicycles via ring closing metathesis sufoximine substituted trienes and dihydropyran derivates
… is an important goal of organic synthesis. Ring-closing metathesis of acyclic dienes is a very effective method for the synthesis of medium-sized carbocycles. In this project, sulfoximine-substituted trienes were proven to be excellent parent compounds for the selective synthesis of …
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Part I. DNA Base and Base Analogue Pairing in Organic Solvents. Part II. Ring Closing Metathesis of Poly-Allylated Glycerol Dendrimers
… cross linking of glycerol dendrimers using the ring closing metathesis (RCM) reaction. An iteratively cross-linked dendrimer was prepared by RCM of an allylated G-3.5 cross-linked dendrimer and the methodology developed for perfect dendrimers was subsequently applied to hyperbranched …
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“Trans-Positioning” Carbons within Strained Caged Bicyclic(s): ROM/RCM (Ring-Opening/Ring-Closing) Metathesis and Dieckmann/Retro-Dieckmann Condensation Routes to a Cis-Decalin Infrastructure
… strained cores. Recent advances in olefin metathesis led to an independent proposal of the now applicable, RRM (Ring-Rearranging Metathesis) for trans-alkenylation purposes. A resourceful Dieckmann/retro-Dieckmann sequence is devised for trans-acylation motives. Finally, this dissertation …
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Annulation strategies for the synthesis of azulenes and polycyclic nitrogen heterocycles
… substituted azulenes have been synthesized via a ring expansion-annulation strategy based on n-halo diazo ketones. The method employs the use of readily available benzenoid starting materials and achieves the synthesis of azulenes substituted on both the five- and seven-membered rings …
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Templat-gesteuerte Synthese von Makrocyclen
… synthesized using a bifunctional template. The ring closing step occurred by metathesis of the preorganized building blocks. The preorganization of the two building blocks simplifies the cyclisation step. After removal of the template the macrocycle can be obtained. Symmetric cyclophanes which …
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Enantioselective total syntheses of acylfulvene, irofulven, and the agelastatins
… and (-)-irofulven, which features metathesis reactions for the rapid assembly of the molecular framework of these anti tumor agents. We discuss (1) the application of an Evans Cu-catalyzed aldol addition reaction using a strained cyclopropyl ketene thioacetal, (2) an efficient enyne …
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The synthesis, characterization and decomposition studies of novel palladacycloalkanes and their precursors
… (n = 2, 3; L = PPh3; L2 = COD, bipy, dppe) by ring closing metathesis (RCM) reactions followed by hydrogenation.
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A novel, versatile D-BCD steroid construction strategy, illustrated by the total syntheses of estrone and desogestrel
… leading to the formation of the steroid C and B rings in a single operation with complete stereocontrol at C9. The ?-keto phosphonates obtained were subsequently subjected to A-ring annelation via a multistep one-pot process. The enantioselective synthesis as well as the racemic total synthesis …
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Asymmetrische Synthese 3-substituierter 4-Methylenproline und Untersuchungen zur Metathese mit vinylischen Sulfoximinen
… part there were investigations towards the cross metathesis or ring closing metathesis of vinylic sulfoximines. The synthesis of (S)-vinylic sulfoximine starting from (S)-N,S-dimethyl-S-phenylsulfoximine succeeded only after activation with a phosphoric acid ester and only in 15% yield. This …
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Modular asymmetric synthesis of functionalized azaspirocycles based on the sulfoximine auxiliary
… construction of the tertiary spiro C-atom bearing a N-atom. The second challenge is the formation of the spirocyclic ring system, namely the carbocycle and the heterocycle. Our synthetic approach to azaspirocycles is characterized by a two-step strategy in which the carbocycle with the future …
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Development and exploration of Schiff base ruthenium carbene catalysts for olefin metathesis
… overview is presented on the history of metathesis catalysts, the current ideas in organometallic thinking and the theoretical accounts on Ru-metathesis catalysts. The second part deals with the synthesis and activity of Schiff base substituted second generation Grubbs catalysts, …
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Higher kekulenes and Polymeric Helicenes
… interested in developing them in polymeric form. Ring closing metathesis (RCM) reaction was used to furnish the helicenes from a suitably designed polymer precursor, poly{4,6-di[(1E)-(2-2H)-propenyl]}-,<italic>m</italic)-phenylene. End group analysis revealed that the polymerization reaction …
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Exploiting imidate ligand effects in transition metal-mediated C-C bond forming processes
… and propargylic nucleophilic substitution, diene ring-closing metathesis and ring-opening metathesis polymerisation and direct arylation reactions, respectively, has been determined. [Au(N-imidate)(NHC)] and [AuBr2(N-imidate)(NHC)] complexes were prepared and the structure and bonding of the …
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Enantioselective synthesis of pretomanid & investigations of Raman spectroscopy for through-tube monitoring of reactions
… of Raman Spectroscopy for Through-Tube Monitoring of Reactions [color illustrations] Continuous-flow chemistry has seen expansive growth and thus requires powerful new analytical techniques. The current commonly-used analytics involve inline analysis at a single point, which can hinder …
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Design and synthesis and testing of conformationally constrained peptidomimetics.
… β-turn or β-strand) by incorporation of a ring or bridge is discussed. The technique of ring closing metathesis as a strategy for cyclisation of peptidomimetics is introduced. Chapter Two surveys β-turn mimics comprised of β-amino acids. The synthesis of novel cyclic peptidomimetics …
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Total Synthesis of Marine Macrolide Mangrolide D
… total synthesis has been accomplished, featuring three robust and interchangeable bond forming reactions: Suzuki cross coupling, ring closing metathesis and α-selective glycosylation reaction. The convergent assembly of chemical building blocks enabled the quick access to mangrolide D and …
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