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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 335 for “"Cyclization"”.
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Silicon-Directed Nazarov Cyclization
A new variation of the Nazarov cyclization has been developed in which an organosilyl group beta to a divinyl ketone directs the incipient double bond to the thermodynamically less stable position. Two general methods for preparing beta-silyl divinyl ketones are reported. Ferric chloride induces …
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Synthesis of taxane cyclization precursors
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1997.
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Synthesis of 2(3H)-furanones via electrophilic cyclization
<p>The electrophilic cyclization of functionally-substituted alkynes is a very promising route to an extraordinary range of medicinally-interesting, functionally-substituted heterocycles and carbocycles. A variety of highly substituted 2(3H)-furanones are readily prepared from 3-alkynoate esters …
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An Anionic 3 + 2 Cyclization-Elimination Route to Cyclopentenes
… reagents in an anionic 3+2 cyclization-elimination route to cyclopentenes.
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Synthesis of indoles via a tandem benzannulation-cyclization strategy
… produce highly-substituted aniline derivatives. Cyclization of the benzannulation products can then be achieved via several alternate procedures leading to indoles that are highly substituted on the six-membered ring. The cyclization approaches investigated as the second step in this tandem …
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Radical cyclization approach to a chemoenzymatic synthesis of morphine
… as a model for use in the well-known Bergman cyclization reaction as a "latent benzene reagent". Bergman cycloaromatization of similar enediynes has been demonstrated and the cyclization temperatures to form the benzenoid diradicals lies in the region 40-70°C. Cache molecular modeling of …
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Silicon-Directed Nazarov Cyclization: Stereochemical, Mechanistic, and Substituent-Compatibility Studies
In the Silicon-Directed Nazarov Cyclization (SDNC) an organosilyl group, attached to a divinyl ketone at a position beta to the carbonyl, directs the location of the double bond in the cyclopentenone ring. Various studies are described that explore the stereochemistry, scope, and mechanism of the …
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The synthesis and cyclization of some new ketones containing nitrogen
no abstract provided by author
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Multicomponent Cyclization Reactions: A General Approach To Dibenzocyclooctadiene Lignan Natural Product
… we applied Pd-catalyzed bis-metallative cyclizations mediated by a [B-Sn] reagent,1-trimethylstannyl-2,5-dimethyl-2,5-diazaborolidine, to access the core DBCOD systems.</p><p>2,2’-Dipropargyl biphenyls are suitable precursors of [B-Sn] reagent mediatedcyclizations and their acetylene …
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Cyclization and cyclopolymerization of silicon-containing dienes ; Functionalization of carbosilane dendrimers
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1997.
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TANDEM BENZANNULATION-CYCLIZATION STRATEGIES FOR THE SYNTHESIS OF HIGHLY SUBSTITUTED INDOLES
Tandem benzannulation-cyclization strategies were developed for the synthesis of highly substituted indoles. The benzannulation strategies involved the reaction of vinylketenes (or aryl ketenes) with ynamides or with ynehydrazides to afford highly substituted phenols via a pericyclic cascade …
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KINETICS OF POLYMER CYCLIZATION REACTION AND NOVEL COVALENT DNA CROSS-LINKING ASSAYS
… I first do an extensive review of polymer cyclization kinetics. Different theories of polymer cyclization kinetics, their assumptions and their predictions are presented along with the predictions of computer simulations. In addition, the experimental results for synthetic and biological …
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Studies on a catalytic cadogan cyclization by PI̳I̳I̳/PV̳=O redox cycling
… adapted this concept to the Cadogan reductive cyclization by using a strained 4-membered phosphetane precatalyst, which proved to be more competent than acyclic and 5-membered analogs for P(III)/P(V)=O redox cycling. A variety of substrates were found to successfully undergo catalytic Cadogan …
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Towards a Formal Total Synthesis of Triptolide Via a Gold-catalyzed Cyclization Cascade
… core of triptolide using a gold-catalyzed cyclization cascade reaction. We explored a number of synthetic routes towards a common linear precursor, and our successes and failures are discussed herein. We also report numerous unsuccessful efforts towards an oxidative gold-catalyzed …
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