Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 26 for “"Sigmatropic Rearrangement"”.
-
1-Aza-1'-Oxa(3,3)sigmatropic rearrangement: Synthesis of N-alkylindoles and 2,3-Dihydro-1h-Pyrrolo (1,2-A) Indole-9-Carboxylates
The {3,3}sigmatropic rearrangement of N-alkyl-N-aryl-O-acetoacetylhydroxylamines gives N-alkyl indoles in moderate yields under mild conditions. The substituted hydroxylamines were prepared by the condensation of aldehydes and ketones with an arylhydroxylamine and reduction of the nitrone so formed …
-
Studies on the 1-Aza-1 Prime -Oxa-(3,3)-Sigmatropic Rearrangement: Synthesis of Ortho-(beta-Oxoalkyl) Anilides and Regiospecifically Substituted Indoles
… O-vinylation of the hydroxamic acid and {3,3}-sigmatropic rearrangement.
-
Investigation of the steric and/or electronic effects associated with the (1,5)-sigmatropic rearrangement of 1-substituted-2,3,4,5-tetraphenyl- 2,4-cyclopentadien-1-ols
… groups played a predictable role in the [l,5]-sigmatropic rearrangement of these compounds. Electron donating groups increased the rate of migration whereas electron withdrawing substituents were responsible for slowing the migration. Likewise, smaller groups accelerated the rate while bulky …
-
The Asymmetric Total Synthesis of Cephalotaxine
… the formation of [3]benzazepines, via the [3,3]-sigmatropic rearrangement of 1-vinyl-2-aryl-aziridines, has been developed and applied to the synthesis of the Cephalotaxus alkaloids. The synthetic approach begins with D-ribose and utilizes the [3,3] sigmatropic rearrangement of a highly …
-
A New Ortho Alkylation Procedure via the 1-Aza-1'-Oxa-(3,3)-Sigmatropic Rearrangement of N,0-Diacyl -N-Arylhydroxylamines: Synthesis of Ortho-(n-Acylamino) Aryl Ketones, Esters and Amides
Made available in DSpace on 2014-12-13T20:10:06Z (GMT). No. of bitstreams: 1 7726745.pdf: 4337017 bytes, checksum: 199232da15b2af0a7d592c560db677c7 (MD5) Previous issue date: 1977
-
Development of novel methodologies utilizing quaternary ammonium salts as catalysts
… development of a phase transfer catalyzed [2,3]-sigmatropic rearrangement of allyloxy carbonyl compounds. Initial investigation focused on identifying viable substrate classes that would undergo selective [2,3]-rearrangement under phase transfer conditions. Under certain conditions, the …
-
Alpha-Oxygenation by Acylation-Rearrangement of Nitrones
The acylation-rearrangement of N-alkylnitrones with acid chlorides and triethylamine affords a new method for the (alpha)-oxygenation of aldehydes and cyclic ketones via (alpha)-acyloxy imines. The reaction apparently proceeds by initial acylation of the nitrone oxygen, proton removal, and …
-
Chirality Transfer in Acyclic Allylic Systems and New Pd-Catalyzed Heck Reaction/C-H Activation Cascades
… an intermolecular reaction. The thermal [2,3] sigmatropic rearrangement of acyclic allylic phosphinites proved to be highly enantioselective, even at 110 °C and led to enantiomerically pure allylic phosphine oxides. The substitution pattern of the substrate and the reaction conditions were …
-
New Methods For The Synthesis Of Oxygen And Nitrogen Containing Heterocycles
… chirality transfer characteristic of a [1,3]- sigmatropic rearrangement. This method was further tested by completing the total synthesis of natural products goniothalesdiol and varitriol.
-
Efforts Toward the Total Synthesis of the Original and Revised Structures of Palau'amine
… via the application of a Diels-Alder/[3,3]-sigmatropic rearrangement of tricyclodecadienes. A cyclization strategy for the formation of the strained trans-fused azabicyclo[3.3.0]octane bicyclic system of the core of the revised structure of palau'amine was also developed within the context …
-
Efforts Toward the Total Synthesis of the Original and Revised Structures of Palau'amine
… via the application of a Diels-Alder/[3,3]-sigmatropic rearrangement of tricyclodecadienes. A cyclization strategy for the formation of the strained trans-fused azabicyclo[3.3.0]octane bicyclic system of the core of the revised structure of palau’amine was also developed within the context …
-
Design, Syntheses, and Bioactivities of Conformationally Locked Pin1 Ground State Inhibitors
… through the use of an Ireland-Claisen [3,3]-sigmatropic rearrangement in nine steps with 13% overall yield from a serine derivative. The Ser-<i>cis</i>-Pro mimic, Boc-SerΨ[(<i>Z</i>)CH=C]Pro–OH, was synthesized through the use of a Still-Wittig [2,3]-sigmatropic rearrangement in 11 steps with …
-
Study of the oxidative degradation of 2,2,3,4,5-pentaphenyl-3- cyclopentenone by various oxidants ; and, [1,5]-sigmatropic phenyl rearrangements in 2- and/or 5-(p- or m-substituted phenyl)-1,3,4-triphenyl-2,4- cyclopentadien-1-ols: electronic effects at the migration terminus
… mixture resulting from their thermal [1,5]- sigmatropic phenyl rearrangements was determined. In this system phenyl could migrate toward either of two positions, and the effect of the substituents upon the direction of migration was investigated to determine the extent of electronic effects …
-
Studies towards the total synthesis of labiatin A
… and oxonium ylide formation followed by [2,3]-sigmatropic rearrangement- is presented. In Chapter II, the successful applications of these two reactions to the enantioselective synthesis of the tricyclic core of labiatin A is described. This is followed by the description of the different …
-
Synthesis, Vinylation and Rearrangement of NH-Isoxazolines and Copper Catalyzed 6 Pi Electrocyclization
… Anderson group is interested in utilizing [3,3] sigmatropic rearrangements to access new N-heterocycles in diastereoselective fashion. The work described in Chapter 1 features a new method for accessing enaminones utilizing a cascade approach that features an N–vinylisoxazoline intermediate that …
-
Cycloaddition-fragmentation mediated pathways to ring D modified 19-norsteroids
… developed which relied on an anionic oxy-Cope rearrangement as the key step. Thus methylenation of the cycloadducts derived from reaction of the dienyl acetate and selected dienophiles (acrolein and methyl vinyl ketone) gave after hydrolysis of the bridgehead ester, substrates which underwent …
-
Developments in Acyl-Claisen Rearrangements and Application to Synthesis
The acyl-Claisen rearrangement is a powerful [3,3]-sigmatropic rearrangement of an allylic amine and an acyl chloride derived ketene. The α,β-substituted-γ,δ-olefinic amide 32 derived from this rearrangement has been demonstrated to be a powerful scaffold for elaboration via a number of routes. …
-
The generation and reactivity of functionalised organozinc carbenoids for cyclopropane synthesis
… carbenoid to participate in a novel [2,3] sigmatropic rearrangement was investigated. The thesis concludes with a summary of the results obtained, a detailed description of the experimental procedures used and the characterization and analysis of the compounds prepared, together with a full …
-
Unique approaches towards the synthesis of polycyclic sesquiterpene targets
… involved the development of a novel [3+3]-sigmatropic rearrangement, to provide access to range of substituted cyclopentanones. Towards this aim, significant progress has been achieved, with late stage compounds having been prepared. Initial studies concentrated specifically on the …
-
Investigation of catalyst effects in enantioselective copper- and rhodium-mediated transformations of α-diazocarbonyl compounds
… cyclopropanation and oxium ylide formation/[2,3]-sigmatropic rearrangement was also explored. Chapter four contains the full experimental details and spectral characterisation of all novel compounds synthesised in this project, while details of chiral stationary phase HPLC analysis and X-ray …
Page 1 of 2