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Showing 1 to 20 of 36 for “"[3+2] cycloaddition"”.

  1. Stereochemical Course of the Tandem [4+2]/[3+2] Cycloaddition of Nitroalkenes

    Seierstad, Mark JasonUniversity of Illinois at Urbana-Champaign2015

    The [4+2] cycloaddition of nitrobutene was further examined with both experimental and theoretical studies. Small, soft Lewis acids (such as Me 3Al) promote endo cycloaddition with the vinyl ether reacting in an s-trans conformation. Most other Lewis acids favor exo cycloaddition due either to …

    uiuc Repository record

  2. Intramolecular (4+2); and tandem intermolecular (4+2);/intramolecular (3+2); cycloaddition of nitroalkenes with achiral and chiral dienophiles

    Senanayake, Chandrawansha Bandara WeerasingheUniversity of Illinois at Urbana-Champaign2011

    … olefins were prepared. Intramolecular cycloadditions with both acyclic and cyclic dienophiles in the presence of SnCl$\sb4$ were investigated. Nitroalkenes tethered with three methylene units to a Z-dienophile afforded trans fused nitronates. The cycloaddition towards larger rings were …

    uiuc Repository record

  3. Inter- and intramolecular (4+2) cycloaddition reactions and tandem inter- and intramolecular (4+2)/intramolecular (3+2)cycloaddition reactions of nitroalkenes

    Moon, Young ChoonUniversity of Illinois at Urbana-Champaign2011

    Both inter- and intramolecular cycloadditions of nitroalkenes with Lewis acid catalysis were investigated. The intramolecular cycloadditions of nitroalkenes were found to be completely stereoselective for trisubstituted nitroalkenes. Intermolecular cycloadditions of aromatic nitroalkenes were found …

    uiuc Repository record

  4. 1. Progress Toward the Synthesis of Vancosamine Using a Tandem [4+2]/[3+2] Cycloaddition. 2. Discussion Boards and Pre-Lecture Quizzes in Organic Chemistry Courses

    Miller, Tyson A.University of Illinois at Urbana-Champaign2015

    Format and number of attempts were varied in online pre-lecture quizzes administered to a first semester non-majors organic chemistry lecture course. Student quiz performance and post-quiz assessment shows significant differences in mastery of material and class preparedness with format and number …

    uiuc Repository record

  5. Tandem Double Intramolecular [4+2]/[3+2] Cycloaddition of Nitro Olefins: Part I: Construction of Piperidine Rings. Part II: Construction of Vicinal Quaternary Stereogenic Centers. Part III: Progress Toward a Total Synthesis of Daphnilactone B

    Baiazitov, Ramil YashnurovichUniversity of Illinois at Urbana-Champaign2015

    … tandem double-intramolecular [4+2]/[3+2] cycloaddition to provide a mixture of two epimeric nitroso acetals. Ozonolysis of the cycloadducts, followed by hydrogenolysis and intramolecular acylation provided the intermediates for the total synthesis that may be elaborated to daphnilactone B. …

    uiuc Repository record

  6. The total syntheses of (+)-crotanecine, (-)-hastanecine and (-)-rosmarinecine utilizing the tandem (4+2)/(3+2) cycloadditions of nitroalkenes

    Thorarensen, AtliUniversity of Illinois at Urbana-Champaign2011

    … is a sequential inter (4+2) /inter (3+2) cycloaddition. The Lewis acid promoted (4+2) cycloaddition between 2-acyloxy nitroalkene 90 and chiral vinyl ether (+)-28 afforded a nitronate which underwent facile (3+2) cycloaddition with dimethyl maleate. The resulting nitroso acetal (${-}$)-96 …

    uiuc Repository record

  7. Synthesis of functionalised sulfonamides

    Mok, B.L.UCL (University College London)2008

    … the use of PFP vinyl sulfonate in a [3+2] cycloaddition with a variety of N-methyl-nitrones, providing access to the corresponding 4C-substituted isoxazolidine in a regio- and diastereoselective manner. Aminolysis of the resultant PFP sulfonate ester then provides functionalised …

    ucl Repository record

  8. Stereoselektive Totalsynthese verschiedener Cassia- und Microcos-Piperidinderivate : Synthese des (-)-Cassins

    Küpper, PatrickUniversität Würzburg

    … wurde mit Hilfe der Tandem Wittig-[3+2]-Cycloaddition geschlossen. Das Reaktionsprodukt ist ein Triazolin, welches in einen Diazoester isomerisiert wurde. Eine nachfolgende Stickstoffextrusion ergab ein vinyloges Urethan. Mit Hilfe einer hochgradig steroselektiven katalytischen Hydrierung …

    wurz-thes Repository record

  9. Preparation and Cycloaddition Reactions of Oxazoline Nitrogen Oxides

    Ashburn, Stephen PatrickUniversity of Illinois at Urbana-Champaign2014

    … with ortho esters or amide acetals. 3 + 2 Cycloaddition reactions of the oxazoline N-oxides and the related pyrroline N-oxides with phenyl isocyanate, dimethyl acetylenedicarboxylate, methyl phenylpropiolate, phenylpropiolonitrile, methyl acrylate, and acrylonitrile were carried out. The …

    uiuc Repository record

  10. I. Efforts Toward the Total Synthesis of the Stemofoline Alkaloids II. Preliminary Development of a Method to Prepare 1,2-Cis-2-Acetamido-2-Deoxyglycopyranoses

    Carra, RyanUniversity of Illinois at Urbana-Champaign2015

    … strategy which is presented utilized a [3+2] cycloaddition of a non-stabilized azomethine ylide as a key step. These studies culminated in the first non-racemic synthesis of the fully-oxygenated tricyclic core of the stemofoline alkaloids. Furthermore, a novel synthetic method to prepare …

    uiuc Repository record

  11. Regio- und stereoselektive Synthese von Sesquiterpenen und hormonell aktiven Cholesterinderivaten

    Schmidt, Arndt W.Technische Universität Dresden

    … wird die Anwendung der Lewis-Säure vermittelten Cycloadditionen von Allylsilanen an alpha,beta-ungesättigte Carbonylverbindungen beschrieben. Das Sesquiterpen Isocomen wurde unter Anwendung der [3+2]-Cycloaddition an Enone synthetisch hergestellt. Die [2+2]-Cycloaddition an Acrylsäurederivate …

    qucosa-diss

  12. The Asymmetric Total Synthesis of Cephalotaxine

    Eckelbarger, Joseph DavidUniversity of Illinois at Urbana-Champaign2015

    … and a diastereoselective intermolecular [3+2] cycloaddition of a non-stabilized azomethine ylide as the key steps. This work has resulted in an asymmetric total synthesis of cephalotaxine in 24 steps and 0.9% overall yield.

    uiuc Repository record

  13. Novel syntheses by directed lithiations of N-Boc benzylamines and cyclopropylamines

    Park, Yong SunUniversity of Illinois at Urbana-Champaign2011

    … of highly functionalized cyclopentane by (3 + 2) cycloaddition and asymmetric synthesis of N-Boc azabicyclic (3.10) hexane was investigated.

    uiuc Repository record

  14. Enantioselective nucleophile-catalyzed cycloadditions

    Wilson, Jonathan E., Ph. D. Massachusetts Institute of TechnologyMassachusetts Institute of Technology2007

    … of an asymmetric nucleophile-catalyzed [2+2] cycloaddition of ketenes with aldehydes. This is the first report of a catalytic enantioselective synthesis of trisubstituted [beta]-lactones. Two enantioselective phosphine-catalyzed [3+2] cycloadditions of allenoates are detailed in Chapter 2. A …

    mit Repository record

  15. Part 1: Progress Toward the Total Synthesis of Platensimycin. Part 2: Aromatic Ions: Carbon-Based Nucleofuges and Chiral Cyclopropenones and Formamides

    Fisher, Ethan Lawrence2011

    … intermediate, and then radical induced [3+2] cycloaddition between a vinyl cyclopropane and pendant olefin to create the core of platensimycin. A revised strategy was employed using a palladium(0) catalyzed Heck cascade and palladium(II) catalyzed alkoxypalladation. The second chapter …

    columbia-diss Repository record

  16. Borox catalysis : a new frontier in chiral Bronsted acid catalysis derived from chiral borate anions

    Gupta, Anil Kumar (Graduate of Michigan State University)2012

    … a novel multi-component asymmetric [3+2] cycloaddition has also been developed. Additionally, an asymmetric epoxidation of aldehydes utilizing an unprecedented chiral SULFOX-BOROX catalyst has been successfully realized. By means of <super>1</super>H, <super>11</super>B NMR and …

    msu Repository record

  17. Synthesis of nitrogen-containing heterocycles using nitro compounds as building blocks: Part I: Synthesis of 3-substituted azepanes. Part II: Synthesis of 1-azoniapropellanes as phase transfer catalysts

    Xie, MinUniversity of Illinois at Urbana-Champaign2010

    … In the first method, the tandem [4+2]/[3+2] cycloaddition of nitroalkene was applied as the key step, wherein a chiral, enantiopure vinyl ether, a nitroalkene and a vinyl ketone were rapidly assembled. The resulting enantiopure nitroso acetals were then elaborated into 1-azoniapropellanes. …

    uiuc Repository record

  18. Synthesis and applications of atropisomeric quinazolinone phosphine ligands

    Dai, Xuedong, 1970-Massachusetts Institute of Technology1998

    … allylic alkylation, phosphine-catalyzed [3+2] cycloaddition of N-tosylimines with 2,3- butadienoate, and asymmetric intramolecular Heck reaction were performed. The 2-methyl group of this ligand series could be activated into the olefin form in the presence of Rh(nbd)2C104. The rhodium complex …

    mit Repository record

  19. An investigation of phase transfer catalysis employing quantitative structure-activity relationships

    Duncan-Gould, Nathan W.University of Illinois at Urbana-Champaign2011

    … as enolate alkylations. The tandem [4+2]/[3+2] cycloaddition of nitroalkenes was applied as the key transformation in the preparation of enantioenriched, tricyclic 1-hydroxy-cyclopentapyrrolizidine ring systems. A three-step parallel synthesis procedure was developed to prepare libraries of …

    uiuc Repository record

  20. [3+2]-Cycloadditions of Azomethine Imines and Ynolates and Progress Towards a Radical Three-Component Cross-Coupling Reaction

    Winterton, Sarah Elizabeth2020

    … The first chapter describes a novel [3+2]-cycloaddition of azomethine imines and ynolates to construct bicyclic pyrazolidinones in high yields and diastereoselectivities. This methodology is the first example in which the azomethine imine acts as a chiral auxiliary to control the …

    utswmed Repository record

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