DOCSLIB.ORG

Propellane Units: Extension of Triptindane Chemistry

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Propellane Units: Extension of Triptindane Chemistry Canadian Journal of Chemistry A Cyclopenta[hi]acephenanthrylene Bearing Two Benzoannelated [3.3.3]Propellane Units: Extension of Triptindane Chemistry Journal: Canadian Journal of Chemistry Manuscript ID cjc-2016-0498.R1 Manuscript Type: Article Date Submitted by the Author: 12-Nov-2016 Complete List of Authors: Hackfort, Thorsten; Universitat Bielefeld Neumann, DraftBeate; Universitat Bielefeld, Department of Chemistry Stammler, Hans-Georg; Universitat Bielefeld, Department of Chemistry Kuck, Dietmar; Universitat Bielefeld, Department of Chemistry polycyclic aromatic hydrocarbons, phenanthrenes, propellanes, McMurry Keyword: reaction, cyclodehydrogenation https://mc06.manuscriptcentral.com/cjc-pubs Page 1 of 28 Canadian Journal of Chemistry A Cyclopenta[ hi ]acephenanthrylene Bearing Two Benzoannelated [3.3.3]Propellane Units: Extension of Triptindane Chemistry Thorsten Hackfort, [a] Beate Neumann, [a] Hans-Georg Stammler [a] and Dietmar Kuck [a,b] * [a] [b] Department of Chemistry and Center of Molecular Materials (CM 2), Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany Draft *E-mail: [email protected] Tel.: +0049 521 106 2060 Fax: +0049 521 106 6146 Dedicated to Professor Reginald H. Mitchell https://mc06.manuscriptcentral.com/cjc-pubs Canadian Journal of Chemistry Page 2 of 28 - 2 - Abstract. The McMurry reaction of triptindan-9-one (2), a three-fold benzoannelated Cs-symmetrical [3.3.3]propellane ketone, gave trans -9,9’-bitriptindanylidene ( 5), a sterically crowded stilbene hydrocarbon bearing two E-oriented triptindane moieties, in good yield. Photoisomerization of 5 generated the corresponding cis -stilbene 8 in a photostationary E/Z-mixture (55 : 45), which adopts a similarly crowded C2- symmetrical conformation that is apparently static on the NMR timescale. Photocyclodehydrogenation of 5 via 8 in benzene solution afforded the title hydrocarbon 6, a 1,2,9,10-tetrahydrocyclopenta[ hi ]acephenanthrylene merged with two triptindane units, in 85% yield. X-ray structure analysis of 6 revealed an essentially planar phenanthrene unit but significant steric repulsion between the pairs of opposite methylene groups of the [3.3.3]propellane cores, giving rise to a C2- symmetrical conformation. ReactionDraft of 2 under modified McMurry conditions (DME instead of THF as a solvent) gave the saturated dimer, 9,9’-bitriptindanyl 7, as a mixture of diastereomers. Attempts to synthesize “columnene” ( 4), an elusive barrelene derivative fused with two triptindane caps, by three-fold McMurry reaction of triptindane-9,10,11-trione ( 3) failed. Keywords: polycyclic aromatic hydrocarbons • phenanthrenes • propellanes • McMurry reaction • cyclodehydrogenation https://mc06.manuscriptcentral.com/cjc-pubs Page 3 of 28 Canadian Journal of Chemistry - 3 - Introduction Among the members of the centropolyindane family,[1,2] monofuso-centrotriindane or C3v-tribenzo[3.3.3]propellane 1 (Figure 1), dubbed “triptindane” by H. W. Thompson on the occasion of its first synthesis in the 1960’s,[3,4] has gained increasing attention since we had developed an independent and versatile synthesis in 1991. [5] Besides various arene-substituted derivatives, [6 −11] those bearing functional groups at the benzylic methylene positions of 1 proved to be important in various aspects and in particular for the extension of the three-dimensional polycyclic framework. [1,12 −14] Whereas the propellane skeleton of 1 exists in a dynamic equilibrium between two [6 −8] 3 C3v -symmetrical conformers, conversionDraft of the benzylic carbons from sp - into sp 2-hybridized atomic centers, such as in the monoketone 2 and the triketone 3,[5] gives rise to rigidified, C3v -symmetrical carbon frameworks. In turn, addition of nucleophiles to 3, in particular, opens an access to a large variety of chiral 9,10,11- trisubstituted triptindane derivatives. [1,10,12 −15] In addition, the particular three- dimensional geometry of the centropolyindanes, bearing their indane wings at nearly right angles in space, does also hold true for the tripindane skeleton. Thus, it appears that the triptindanes are awaiting further exploration as a revival of [3.3.3]propellane chemistry [1,16 −26] and as an extension of the permanently expanding field of polycyclic aromatic compounds. [27 −31] Figure 1 A variant of this theme is the conceivable dimerization of the triptindane ketones. The work presented here was inspired by the idea to subject the readily accessible https://mc06.manuscriptcentral.com/cjc-pubs Canadian Journal of Chemistry Page 4 of 28 - 4 - triketone 3 to a McMurry reaction. [32 −36] Such a reductive “dimerization” of the triptindane skeleton was envisioned to afford the double [3.3.3]propellane-fused barrelene derivative 4, a hypothetical hydrocarbon that would bear a highly rigidified molecular framework with three strained but shielded and strictly parallel double bonds, which we dubbed “columnene” (Figure 1). Whereas this aim remained elusive in our hands, we found that the related monoketone 2 does undergo dimerization reactions under McMurry conditions. In this way, we synthesized the bis-propellane 5 and achieved its photocyclodehydrogenation to a novel three-dimensional polycyclic aromatic hydrocarbon, the cyclopenta[ hi ]acephenanthrylene 6, in which two triptindane units are peri -fused to by a common benzene core. Experimental Draft General. Melting points (uncorrected) were measured with an Electrothermal melting point apparatus. IR spectra were recorded with a Perkin Elmer IR-841 instrument. NMR spectra were measured with a Bruker DRX 500 instrument ( 1H, 500 MHz, 13 C, 125.7 MHz) or a Bruker AM 250 instrument ( 13 C, 62.3 MHz). Mass spectra were recorded with a Fisons VG Autospec X double-focusing mass spectrometer. Accurate mass measurements were carried out with the Autospec instrument (EI). UV absorption spectra were recorded with Perkin-Elmer Lambda 40 spectrophotometer. Combustion analyses were carried out with a Perkin Elmer 240 instrument by Zentrale Analytik of the Chemistry Department of Bielefeld University. The photoreactors after de Meijere used were manufactured by Otto Fritz (Normag). [51,52] Column chromatography was performed using Merck and Macherey- Nagel silica gel (0.063-0.200 mm). Medium-pressure chromatography (MPLC) was performed with a high-pressure pump Besta E 100, a UV detector Besta UV, a Besta https://mc06.manuscriptcentral.com/cjc-pubs Page 5 of 28 Canadian Journal of Chemistry - 5 - pulsation attenuator, a pre-column 8 × 100 mm, column 20 × 500 mm, and stationary phases ICN Silica 18-32, 60 Å; 12-26, 60 Å; LiChroPrep Si 60, 40-60 µm (Merck); flowrate 6 mL min −1. Thin-layer chromatography was carried out with TLC foils 60 F254 (Merck) and UV detection. Dichloromethane, petroleum ether (60 −80 °C), ethyl acetate, diethyl ether and cyclohexane were distilled before use. All other chemicals were purchased from Alfa Aesar or Sigma-Aldrich and used as delivered. Reactions requiring anhydrous conditions were carried out in oven-dried glassware under argon. trans -9-(9 H,10 H-4b,9a-([1,2]Benzenomethano)indeno[1,2-a]inden-9’-ylideno)- 9H,10 H-4b,9a-([1,2]benzenomethano)indeno[1,2-Draft a]indene ( trans-9,9’- Bitriptindanylidene, 5). Tetrahydrofuran (THF p.a., 200 mL) was stirred and cooled in an ice bath under argon, while titanium tetrachloride (13.1 mL, 22.7 g, 120 mmol) was added slowly through a dropping funnel. Stirring of the light-yellow suspension formed in this way was continued while zinc dust (14.3 g, 219 mmol) was added in small portions, turning the color of the mixture from yellow to black. The ice bath was removed and the mixture was heated to reflux temperature for 2 h under continued stirring. Then a solution of triptindanone 2[5] (1.60 g, 5.20 mmol) in THF (10 mL) was added dropwise and the resulting reaction mixture was heated under reflux for a further 12 h. The mixture was allowed to cool to ambient temperature. Then concentrated hydrochlorid acid (100 mL) was added under vigorous stirring and additional external cooling in a water/ice bath. This resulted in a foamy and deeply violet solution, which was extracted repeatedly with dichloromethane. The combined organic layers were de-acidified with saturated aqueous sodium bicarbonate and then with brine and dried over magnesium sulfate. The solvent was removed under https://mc06.manuscriptcentral.com/cjc-pubs Canadian Journal of Chemistry Page 6 of 28 - 6 - reduced pressure to give a beige solid, which was purified by medium-pressure chromatography (petroleum ether/EtOAc 5 : 1), affording the pure trans -hydrocarbon 1 5 (1.12 g, 74%). Rf(CH 2Cl 2) 0.75, m.p. 347 °C (decomp.). H NMR (500 MHz, CDCl 3, TMS): δ = 7.85 (d, J = 7.6 Hz, 2 H; 8-H, 8’-H), 7.69 (d, J = 7.2 Hz, 2 H; 5-H, 5’-H), 7.55 (d, J = 7.6 Hz, 4 H; 4-H, 4’-H, 15-H, 15’-H), 7.35 (t, J = 7.2, J = 0.8 Hz, 2 H; 6-H, 6’-H), 7.31 (t, J = 7.19, J = 1.0 Hz, 2 H; 7-H, 7’-H), 7.15 (t, 3J = 7.4 Hz, 4 H; 3-H, 3’H, 14-H, 14’-H), 7.00 (t, 3J = 7.5 Hz, 4 H; 2-H, 2’H, 13-H, 13’-H), 6.76 (d, 3J = 7.5 Hz, 4 H; 1-H, 1’-H, 12-H, 12’-H); 3.39 and 3.24 (AB, |J| = 16,3 Hz, 8 H; 10-H, 10’H, 11-H, 13 11’-H) ppm. C NMR (126 MHz, CDCl 3, TMS): δ = 148.8 (C), 144.5 (C), 143.6 (C), 142.8 (C), 141.2 (C), 128.6 (CH), 127.0 (CH), 126.7 (CH), 126.5 (CH), 126.3 (CH), 124.7 (CH), 123.9 (CH), 123.3 (CH),Draft 78.3 (C), 71.3 (C), 44.0 (CH 2) ppm. MS (EI, 70 eV): m/z (%) 584 (100, [M +• ]), 585 (53), 493 (6), 293 (16), 292 (24), 291 (49), 290 (10), 289 (14), 276 (6), 215 (6), 202 (9), 203 (8), 91 (10).
Load more

Recommended publications
  • Transition Metal Complexes of Dicyanoacetylene
    Louisiana State University LSU Digital Commons LSU Historical Dissertations and Theses Graduate School 1971 Transition Metal Complexes of Dicyanoacetylene: a Study of the Reaction Chemistry of Low Valence States of the Transition Metals, Platinum, Palladium, Nickel, Rhodium, and Iridium. Gregory Lloyd Mcclure Louisiana State University and Agricultural & Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_disstheses Recommended Citation Mcclure, Gregory Lloyd, "Transition Metal Complexes of Dicyanoacetylene: a Study of the Reaction Chemistry of Low Valence States of the Transition Metals, Platinum, Palladium, Nickel, Rhodium, and Iridium." (1971). LSU Historical Dissertations and Theses. 2001. https://digitalcommons.lsu.edu/gradschool_disstheses/2001 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. 71-29,382 McCLURE, Gregory Lloyd, 1993- TRANSITION METAL COMPLEXES OF DICYANOACETYLENE: A STUDY OF THE REACTION CHEMISTRY OF LOW VALENCE STATES OF THE TRANSITION METALS, PLATINUM, PALLADIUM, NICKEL, RHODIUM, AND IRIDIUM. The Louisiana State University and Agricultural and Mechanical College, Ph.D., 1971 C hem i stry, inorgan ic University Microfilms, A XEROX Company , Ann Arbor. Michigan THIS DISSERTATION HAS BEEN MICROFILMED EXACTLY AS RECEIVED TRANSITION
    [Show full text]
  • Synthesis and Transformations of a Few 9-(Pent-4-Yn-1-Yl)Anthracene-Type Systems
    The Free Internet Journal Paper for Organic Chemistry Archive for Arkivoc 2018, part vii, 0-0 Organic Chemistry Synthesis and transformations of a few 9-(pent-4-yn-1-yl)anthracene-type systems Eason M. Mathew, Tomson Devassia, Sreedharan Prathapan, and Perupparampil A. Unnikrishnan* Department of Applied Chemistry, CUSAT, Kochi-22, India Email: [email protected] Received 05-24-2018 Accepted 11-04-2018 Published on line 12-27-2018 Abstract 9-(Pent-4-yn-1-yl)anthracene-type compounds can potentially undergo intramolecular Diels-Alder (IMDA) reaction to form 9,11-annulated dibenzobarrelenes. Herein we report the synthesis and IMDA reactions of several heteroatom incorporated 9-(pent-4-yn-1-yl)anthracene-type compounds. Keywords: Dibenzobarrelenes, Intramolecular Diels-Alder (IMDA) reaction, tethered barrelenes, fused-ether, ester, sulfide and sulfone, 1H and 13C NMR DOI: https://doi.org/10.24820/ark.5550190.p010.637 Page 1 ©ARKAT USA, Inc Arkivoc 2018, part vii, 0-0 Mathew, E. M. et al. Introduction Synthesis of bicyclo[2,2,2]octa-2,5,7-triene (barrelene) was first reported by Zimmerman1 et al in 1960. Its barrel-shaped array of molecular orbitals and three ethylene units that are like staves attached to the two methine units attracted the attention of chemists. Synthesis of several barrelene derivatives, especially dibenzobarrelenes, exploited Diels-Alder reaction.2-7 Intramolecular Diels-Alder (IMDA) reaction of suitably substituted anthracenes to give tricyclic systems that may be regarded as annulated barrelenes was first reported by Meek and Dann.8,9 In 1980, Ciganek5 reported a systematic investigation on the synthesis of 9,11- bridged dibenzobarrelene via IMDA reaction (Scheme 1).
    [Show full text]
  • Iificrlgan STATE L'rwebseey Tsuyoghi Kakihama 1966
    SYNTRESIES Aflfi AC LE CATALYZED REA RRARGEMEMT @F M GHQ“ 52$..BESI'EWTEB F: {CYCLG' ($2.25.) OCIA- 5 , '1’ . D iEN - 2. .. 0L3 Tit-tests {fort- {’{m Deqm 3% M . 5. iifiCRlGAN STATE L‘RWEBSEEY Tsuyoghi Kakihama 1966 v7 u“. 2-” ¥ r' LIBRARY ’QTHESIS Michigan State University ABSTRACT SYNTHESIS AND ACID CATALYZED REARRANGEMENT OF HIGHLY SUBSTITUTED BICYCLO[2.2.2]OCTA-5,7-DIEN-2-OLS by Tsuyoshi Kakihana The purpose of this investigation was to synthesize func- tional derivatives of bicyclo[2.2.2]octa-2,5,7-triene ("barrelene") (2). The following scheme was proposed as a route to the desired barrelene derivatives. V R1 H . 2 ‘:TL + R3CECR4'————> AEZ;}//’ 4 \ / R2 R/ R3 R1, R2 = CH3 R3, R4 = "COOCH3 or or R1, R2 = H R3, R4 = ‘CsHS or R3CECR4 = benzyne reductionL acid (OCH /R ——.fi-r—3-> 2 . R4 _ R1 R3 Although this route to barrelenes has thus far been un- successful, various stages of the synthesis have worked Tsuyoshi Kakihana depending on the nature of R groups and a study of these intermediates has led to some unusual rearrangements and bi— and tricyclic systems. Diels-Alder reaction of 3,4,6,6-tetramethylcyclohexa- 2,4-dienone (5) and dimethyl acetylenedicarboxylate gave 3,3,7,8-tetramethyl-5,6-dicarbomethoxybicyclo[2.2.2]octa-5,7- dien-Z-one, 1. 1,5,5,4,7,8-Hexamethyl—5,6-dicarbomethoxybi- cyclo[2.2.2]octa-S,7-dien-2-one, 2, was obtained in a simi- lar manner from 2,3,4,5,6,6-hexamethylcyclohexa-2,4—dienone (4) and dimethyl acetylenedicarboxylate.
    [Show full text]
  • Cheminformatics for Genome-Scale Metabolic Reconstructions
    CHEMINFORMATICS FOR GENOME-SCALE METABOLIC RECONSTRUCTIONS John W. May European Molecular Biology Laboratory European Bioinformatics Institute University of Cambridge Homerton College A thesis submitted for the degree of Doctor of Philosophy June 2014 Declaration This thesis is the result of my own work and includes nothing which is the outcome of work done in collaboration except where specifically indicated in the text. This dissertation is not substantially the same as any I have submitted for a degree, diploma or other qualification at any other university, and no part has already been, or is currently being submitted for any degree, diploma or other qualification. This dissertation does not exceed the specified length limit of 60,000 words as defined by the Biology Degree Committee. This dissertation has been typeset using LATEX in 11 pt Palatino, one and half spaced, according to the specifications defined by the Board of Graduate Studies and the Biology Degree Committee. June 2014 John W. May to Róisín Acknowledgements This work was carried out in the Cheminformatics and Metabolism Group at the European Bioinformatics Institute (EMBL-EBI). The project was fund- ed by Unilever, the Biotechnology and Biological Sciences Research Coun- cil [BB/I532153/1], and the European Molecular Biology Laboratory. I would like to thank my supervisor, Christoph Steinbeck for his guidance and providing intellectual freedom. I am also thankful to each member of my thesis advisory committee: Gordon James, Julio Saez-Rodriguez, Kiran Patil, and Gos Micklem who gave their time, advice, and guidance. I am thankful to all members of the Cheminformatics and Metabolism Group.
    [Show full text]
  • TRIPTYCENE- and BIPHENYLENE-BASED BIFUNCTIONAL LEWIS ACIDS AS ANION RECEPTORS a Dissertation by CHANG-HONG CHEN Submitted to Th
    TRIPTYCENE- AND BIPHENYLENE-BASED BIFUNCTIONAL LEWIS ACIDS AS ANION RECEPTORS A Dissertation by CHANG-HONG CHEN Submitted to the Office of Graduate and Professional Studies of Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Chair of Committee, François P. Gabbaï Committee Members, Michael B. Hall Oleg V. Ozerov Melissa A. Grunlan Head of Department, Simon W. North August 2018 Major Subject: Chemistry Copyright 2018 Chang-Hong Chen ABSTRACT The chemistry of main group-based polydentate Lewis acids has drawn considerable attention over the past few decades, owing to application in anion sensing, anion transport, small molecule activation and catalysis. Bidentate Lewis acids featuring the rigid 1,8-naphthalenediyl or ortho-phenylene backbones are the most studied examples of such systems. Owing to the short spacing of the two Lewis acidic sites, these derivatives can only chelate monoatomic anions or polyatomic anions amenable to μ(1,1) ligation. Bearing in mind that this limitation could be overcome through modification of the backbone architecture, we have recently become interested in bidentate Lewis acids with an increased separation between the Lewis acidic centers. It occurred to us that triptycene and biphenylene backbones may offer extended separation between Lewis acidic centers, which may facilitate the selective complexation of larger anions. In this thesis, we report on the chemistry of triptycene- and biphenylene-based diboranes as large-bite bidentate Lewis acids for the μ(1,2) complexation of the cyanide anion as well as hydrazine. The results demonstrate that the biphenylene platform can be used as a support for hybrid ditopic Lewis acids containing both borane and borinic acid moieties.
    [Show full text]
  • Annulenes, Barrelene, Aromatic Ions and Antiaromaticity
    Annulenes, Barrelene, Aromatic Ions and Antiaromaticity Annulenes Monocyclic compounds made up of alternating conjugated double bonds are called annulenes. Benzene and 1,3,5,7-cyclooctatetraene are examples of annulenes; they are named [6]annulene and [8]annulene respectively, according to a general nomenclature system in which the number of pi-electrons in an annulene is designated by a number in brackets. Some annulenes are aromatic (e.g. benzene), but many are not due to non- planarity or a failure to satisfy the Hückel Rule. Compounds classified as [10]annulenes (a Hückel Rule system) serve to illustrate these factors. As shown in the following diagram, 1,3,5,7,9-cyclodecapentaene fails to adopt a planar conformation, either in the all cis-configuration or in its 1,5-trans-isomeric form. The transannular hydrogen crowding that destabilizes the latter may be eliminated by replacing the interior hydrogens with a bond or a short bridge (colored magenta in the diagram). As expected, the resulting 10 π-electron annulene derivatives exhibit aromatic stability and reactivity as well as characteristic ring current anisotropy in the nmr. Naphthalene and azulene are [10]annulene analogs stabilized by a transannular bond. Although the CH2bridged structure to the right of naphthalene in the diagram is not exactly planar, the conjugated 10 π-electron ring is sufficiently close to planarity to achieve aromatic stabilization. The bridged [14]annulene compound on the far right, also has aromatic properties. Barrelene Formulation of the Hückel rule prompted organic chemists to consider the possible aromaticity of many unusual unsaturated hydrocarbons. One such compound was the 6 π- electron bicyclic structure, now known as barrelene.
    [Show full text]
  • Xerox University Microfilms, Ann Arbor,Michigan 48106
    77-2525 VOLZ, William Edward, 1947- STRAINED ALICYCLIC HYDROCARBONS: SYNTHESIS, CHLOROSULFONYL ISOCYANATE ADDITIONS AND ELECTRONIC PROPERTIES. The Ohio State University, Ph.D., 1976 Chemistry, organic Xerox University Microfilms,Ann Arbor, Michigan 48106 STRAINED ALICYCLIC HYDROCARBONS: SYNTHESIS, CHLOROSULFONYL ISOCYANATE ADDITIONS AND ELECTRONIC PROPERTIES DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University by William Edward Volz, B.S. ***** The Ohio State University 1976 ... Reading Committee: Approved by Dr. Leo A. Paquette Dr. Gideon Fraenkel Dr. John S. Swenton Adviser Department of Chemistry DEDICATION Monica, Tracy, and ACKNOWLEDGMENTS I am truly grateful to Professor Leo A. Paquette for his direction, encouragement and enthusiasm during this -work. The stimulating atmo­ sphere provided by the research group he has attracted is something that I am very proud to have experienced. I wish to thank my friend Mike Geekle for all of the nmr work he did for me. I especially value the companionship he gave me and my family. The photoelectron spectra and related molecular orbital calculations are courtesy of Professor Rolf Gleiter and Dr. Peter Bischof at the Tech- nischen Hochschule Damstadt, West Germany. I sincerely appreciate the sacrifices Monica, Tracy and Eric made to my education, and the confidence Monica, my parents and my parents-in-law had in me. I would also like to acknowledge The Ohio State University and the people of Ohio for their financial support. VITA October 15, 1947 ........... B o m - Des Moines, Iowa 1970 .......................... B. S., The Iowa State University, Ames, Iowa 1970-1974.....................
    [Show full text]
  • The Synthesis of Carbacyclic Silanes Via Organosilicon Reactive Intermediates Michael J
    Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1984 The synthesis of carbacyclic silanes via organosilicon reactive intermediates Michael J. Vuper Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Organic Chemistry Commons Recommended Citation Vuper, Michael J., "The synthesis of carbacyclic silanes via organosilicon reactive intermediates " (1984). Retrospective Theses and Dissertations. 7737. https://lib.dr.iastate.edu/rtd/7737 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. INFORMATION TO USERS Tliis reproduction was made from a copy of a document sent to us for microfilming. While the most advanced technology has been used to photograph and reproduce this document, the quality of the reproduction is heavily dependent upon the quality of the material submitted. The following explanation of techniques is provided to help clarify markings or notations which may appear on this reproduction. 1. The sign or "target" for pages apparently lacking from the document photographed is "Missing Page(s)". If it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages. This may have necessitated cutting through an image and duplicating adjacent pages to assure complete continuity. 2. When an image on the film is obliterated with a round black mark, it is an indication of either blurred copy because of movement during exposure, duplicate copy, or copyrighted materials that should not have been filmed.
    [Show full text]
  • Bent Bonds (Τ) and the Antiperiplanar Hypothesis the Chemistry of Cyclooctatetraene and Other C8H8 Isomers
    Article Cite This: J. Org. Chem. 2018, 83, 5751−5755 pubs.acs.org/joc Bent Bonds (τ) and the Antiperiplanar HypothesisThe Chemistry of Cyclooctatetraene and Other C8H8 Isomers † ‡ Ghislain Deslongchamps and Pierre Deslongchamps*, † Department of Chemistry, University of New Brunswick, Fredericton, NB, E3B 5A3, Canada ‡ Departement́ de Chimie, UniversitéLaval, Quebec,́ QC, G1 V 0A6, Canada *S Supporting Information ABSTRACT: The bent bond/antiperiplanar hypothesis (BBAH) has been applied to the thermal rearrangements of cyclooctatetraene and related C8H8 isomers. This novel orbital model shows that pyramidal singlet diradical intermediates produced from thermal vibrational states of C8H8 isomers account for their chemical reactivity. ■ INTRODUCTION hyperconjugation5 suggeststhatitispossibletohave τ Cyclooctatetraene (COT) is capable of three fundamental antiperiplanar electronic delocalization involving bonds and that it can be applied to the Diels−Alder reaction,6 [1,3]- structural changes referred to as ring inversion, bond shifting, 7 and valence isomerization1,2 (Figure 1). The first of these sigmatropic alkyl thermal rearrangements, and high-temper- ature isomerization of benzenoid polycyclic aromatic hydro- carbons.8 We have also shown that this model can rationalize the aldol addition reaction of ketones and aldehydes containing an α-alkoxy stereocenter9,10 as well as the important glycosylation step in carbohydrates.9 We wish now to report that the dynamic properties of COT and other C8H8 isomers can also be readily understood through the BBAH as a simple alternative model of structure and reactivity. ■ RESULTS AND DISCUSSION τ-Bond Electronic Delocalization in COT. COT exists in a tub shaped conformation and, based on its description using σ−π bond orbitals, cannot have proper conjugation.
    [Show full text]
  • Microwave-Assisted Synthesis and Reactivity of Porphyrins
    Send Orders for Reprints to [email protected] Current Organic Synthesis, 2014, 11, 89-109 89 Microwave-Assisted Synthesis and Reactivity of Porphyrins Marta Pineiro* Departamento de Química, Universidade de Coimbra, Rua Larga 3004-535 Coimbra, Portugal Abstract: This paper describes past and current microwave-assisted methodologies for the synthesis of porphryins and porphyrin derivatives, including porphyrin precursors such as dipyrromethanes. The review is organized in two main topics, porphyrin synthesis and porphyrin reactivity under microwave irradiation and covers solventless and solution reactions. Keywords: Hydroporphyrin, metalloporphyrin, microwave irradiation, microwave synthesis, porphyrin, tetrapyrrolic macrocycles. 1. INTRODUCTION stituted beta-porphyrins were obtained via cyclisation of linear The acknowledgement that porphyrins and related compounds tetrapyrroles, b-bilenes and a,c-biladienes [15] could be referred. had essential functionalities in nature prompted the interest in mul- Microwave-assisted organic chemistry has grown in the last tiple scientific domains, from the deeper comprehension of those decades as a valuable and versatile tool for organic chemists [16]. functions to the investigation of new applications which comprise In general, compared to conventional heating methods, microwave several analytical uses [1], dye-sensitised solar cells [2], molecular heating has been shown to drastically reduce reaction times, in- electronics and non-linear optics [3], sensors of small molecules crease reaction yields and enhance product selectivity, mostly re- such as O2, NO, NH3 or phosphines [4], catalysts in oxidation and ducing undesirable side reaction products. Microwave irradiation is, photo-oxidation reactions [5], and several biological applications in our days, fully recognized as a useful tool for organic synthesis such as photodynamic therapy of cancer, imaging and boron neu- used in multi-step total synthesis [17], medicinal chemistry and tron-capture therapy [6].
    [Show full text]
  • Organic Seminar Abstracts
    1364 SUiMr^e^ L I B RARY OF THE U N IVLRSITY OF ILLINOIS Q.54-7 1964 Return this book on or before the Latest Date stamped below. Theft, mutilation, and underlining of books are reasons for disciplinary action and may result in dismissal from the University. University of Illinois Library L161— O-1096 \ Digitized by the Internet Archive in 2012 with funding from University of Illinois Urbana-Champaign http://archive.org/details/organicseminarab1964univ SEMINAR TOPICS Summer Session, 196^ The Reaction of a-Diketones with Trialkyl Phosphites Earl G. Alley 1 The Mechanism of the Wallach Rearrangement David A. Durand 8 -m> Aromatic Oxocarbon Anions ) Monocyclic (CO ; n Thomas P. Doherty 17 Two Novel Unsaturated Bicyclic Systems M. A. Lintner 26 The Structure of Pimaricin Ping Huang 5 l\ The Schmidt Reaction with Ketones Allan C. Buchholz 4l Stable Acyclic Aliphatic Carbonlum Ions D. Druliner 50 Structure and Syntheses in the Caryophyllene Family R. L. Keener 59 Carbon 15 Nuclear Magnetic Resonance Leigh E. Walker 68 P . THE REACTION OF a-DIKETONES WITH TRIALKYL PHOSPHITES .Reported by Earl G. Alley June 24, 1964 Introduction ,, --Interest in the reactions of esters of phosphorous acid with car- bonyl compounds has arisen mainly because the products undergo Arbuzov type rearrange- ments (l). In addition to the reactions of trialkyl phosphites with a-dicarbonyl compounds , which are the subject of this review, the reactions of trialkyl phosphites with alkyl halides, alcohols, aldehydes, ketones and anhydrides have been studied (l). The reactions of trialkyl phosphites with p-quinones give products the structures of which are the subject of controversy (2,3,4) .
    [Show full text]
  • Synthesis and Photochemical Transformations of a Few Tethered Barrelenes
    SYNTHESIS AND PHOTOCHEMICAL TRANSFORMATIONS OF A FEW TETHERED BARRELENES Thesis submitted to the Cochin University of Science and Technology In partial fulfilment of the requirements for the degree of Doctor of Philosophy In Chemistry In the Faculty of Science By Eason M. Mathew Under the supervision of Dr. P. A. Unnikrishnan DEPARTMENT OF APPLIED CHEMISTRY COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY KOCHI – 682 022, Kerala, INDIA July 2013 DECLARATION I hereby declare that the work presented in the thesis entitled “Synthesis and Photochemical Transformations of a few Tethered Barrelenes” is the result of genuine research carried out by me under the supervision of Dr. P. A. Unnikrishnan, Assistant Professor of Organic Chemistry, Department of Applied Chemistry, Cochin University of Science and Technology, Kochi‐22, and the same has not been submitted elsewhere for the award of any other degree. Kochi-22 Eason M. Mathew July 1, 2013 DEPARTMENT OF APPLIED CHEMISTRY COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY COCHIN – 682 022, KERALA, INDIA Dr. P. A. Unnikrishnan Assistant Professor Ph:- 0484-2575804 email: [email protected] CERTIFICATE This is to certify that the thesis entitled “Synthesis and Photochemical Transformations of a few Tethered Barrelenes” is a genuine record of research work carried out by Mr. Eason M. Mathew, under my supervision, in partial fulfilment of the requirements for the degree of Doctor of Philosophy of Cochin University of Science and Technology, and further that no part thereof has been presented before for the award of any other degree. Kochi-22 P. A. Unnikrishnan July 1, 2013 (Supervising Guide) Acknowledgements I would like to take this opportunity to acknowledge and extend my sincere thanks for those who help me to make this Ph.D.
    [Show full text]