DOCSLIB.ORG

Next Generation 'Frustrated Lewis Pairs'

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Next Generation 'Frustrated Lewis Pairs' NEXT GENERATION ‘FRUSTRATED LEWIS PAIRS’ by Daniel J. Scott A dissertation submitted to the Department of Chemistry of Imperial College London for the degree of Doctor of Philosophy December 2016 1 Abstract The past decade has seen the emergence of a new concept in main-group chemistry: ‘frustrated Lewis pairs’ (FLPs) are combinations of a Lewis acid (LA) and base (LB) that are prevented from forming the classically-expected adduct. By displaying simultaneously acidic and basic behaviour, these systems have been shown to be capable of activating a wide range of chemical bonds, in a manner highly reminiscent of transition-metal (TM) compounds. Chief among these reactions is the activation of H2, which can then be transferred from the FLP to an appropriate substrate. FLPs have thus provided an entirely new class of homogeneous hydrogenation catalysts, which do not require the use of TMs. Nevertheless, prior to the work described herein, such catalysis had not been successfully applied to the hydrogenation of organic carbonyl functional groups, and had been found to be extremely sensitive to the presence of moisture. This thesis describes work that has successfully overcome these limitations. Chapter 1 provides an introduction to the field of FLP chemistry, including a general summary of the topic, and a more detailed overview of catalytic hydrogenation mediated by FLPs. Chapter 2 describes the development of novel FLPs based on the combination of strong triarylborane LAs and weak ethereal solvent LBs. These systems are shown to be highly effective for the hydrogenation of a variety of substrates, including the first examples of both FLP-catalysed hydrogenation of ketones and aldehydes, and moisture-tolerant FLP-catalysed hydrogenation. Chapter 3 describes the design and preparation of alternative systems incorporating Sn(IV)-based LAs, whose use in FLP-mediated H2 activation has not previously been documented. These too are shown to be tolerant of moisture, and to be suitable for the hydrogenation of C=O, C=N and C=C bonds. Chapter 4 provides full experimental details for the procedures described in Chapter 2 and Chapter 3. 2 Declaration The work described herein was performed at Imperial College London during the period between October 2013 and October 2016 inclusive, under the supervision of Dr Andrew Ashley and Dr Matthew Fuchter. All results were obtained by the author (Mr Daniel Scott) unless explicitly stated otherwise, and have not previously been submitted in pursuit of any other degree at any institution. Daniel John Scott December 2016 Copyright The copyright of this thesis rests with the author and is made available under a Creative Commons Attribution Non-Commercial No Derivatives licence. Researchers are free to copy, distribute or transmit the thesis on the condition that they attribute it, that they do not use it for commercial purposes and that they do not alter, transform or build upon it. For any reuse or redistribution, researchers must make clear to others the licence terms of this work. 3 Acknowledgements First and foremost, I would like to thank my academic supervisors for getting me to this point. Without Andy and Matt’s constant support, guidance and intellectual input this thesis would not exist. I would also like to acknowledge all the various colleagues with whom I have been lucky enough to share an office during the course of this project: they have graciously expended a huge amount of effort first to teach me how to function in a lab setting, and then to help me stay (relatively) sane. Almost everybody who falls into this category has earned a special mention, but in order to avoid a rambling Oscars-style outpouring I’ll keep it generic: thank you all (you know who you are). Finally, while technical support for this project has been provided by a number of people, I have to single out Peter Haycock his assistance with NMR. For the past several years he has tolerated my frankly unreasonable demands on his time, expertise, and equipment with unfailing good humour. Without his help, this project could not have been nearly as successful. 4 Abbreviations 2-MeTHF 2-methyltetrahydrofuran APCI-MS atmospheric pressure chemical ionisation mass spectrometry Ar generic aryl group Bn benzyl; phenylmethyl Bu n-butyl col 2,4,6-collidine; 2,4,6-trimethylpyridine Cy cyclohexyl DABCO 1,4-diazabicyclo[2.2.2]octane DCB 1,2-dichlorobenzene DFB 1,2-difluorobenzene DFT density functional theory Dipp 2,6,-diisopropylphenyl DMF N,N-dimethylformamide DMSO dimethylsulfoxide EDG electron-donating group Et ethyl EWG electron-withdrawing group FLP frustrated Lewis pair FXyl 3,5-trifluoromethylphenyl HMBC heteronuclear multiple bond correlation Hex n-hexyl HOMO highest occupied molecular orbital I nuclear spin iBu iso-butyl iPr iso-propyl J coupling constant LA Lewis acid LB Lewis base 5 LUMO lowest unoccupied molecular orbital lut 2,6-lutidine; 2,6-dimethylpyridine m/z mass/charge ratio Me methyl Mes mesityl; 2,4,6-trimethylphenyl Ms mesyl; O2SMe MS mass spectrometry MS-ToF mass spectrometry – time of flight NHC N-heterocyclic carbene NMR nuclear magnetic resonance Np neopentyl; CH2CMe3 Ph phenyl Pr n-propyl R generic organic group F R C(CF3)3 RT room temperature T1 spin-lattice relaxation time tBu tert-butyl Tf trifluoromethanesulfinate; O2SCF3 THF tetrahydrofuran TM transition metal TMP 2,2,6,6-tetramethylpiperidyl TMS tetramethylsilane Trip 2,4,6-triisopropylphenyl Ts tosyl; 4-methylphenylsulfonyl VT variable temperature XRD X-ray diffraction xs excess D-CD D -cyclodextrin G chemical shift Hr relative permittivity 6 Units °C degrees Celcius Å Ångströms atm atmospheres bar bar cal calories d days g grams h hours Hz Hertz J Joules K Kelvin L litres M molar (mol dm–3) mol moles ppm parts per million s seconds 7 Table of contents Abstract .................................................................................................................................................. 2 Declaration ............................................................................................................................................. 3 Copyright ................................................................................................................................................ 3 Acknowledgements ................................................................................................................................ 4 Abbreviations ......................................................................................................................................... 5 Units ....................................................................................................................................................... 7 Table of contents ................................................................................................................................... 8 List of Figures ....................................................................................................................................... 10 List of Schemes ..................................................................................................................................... 13 List of Tables ......................................................................................................................................... 19 Chapter 1 - Introduction ....................................................................................................................... 20 Chapter 1.1 - Putting FLPs in context: main group mimics of transition metals .............................. 20 Chapter 1.2 - Introduction to frustrated Lewis pair chemistry ........................................................ 24 Chapter 1.2.1 - Stoichiometric FLP reactivity ............................................................................... 24 Chapter 1.2.2 - Catalytic FLP reactivity ........................................................................................ 27 Chapter 1.3 - Some historical context for FLP chemistry ................................................................. 30 Chapter 1.4 - Hydrogenation catalysis using FLPs ............................................................................ 32 Chapter 1.4.1 - Stoichiometric FLP H2 activation ......................................................................... 32 Chapter 1.4.2 - Catalytic FLP H2 activation .................................................................................. 35 Chapter 1.4.3 - Aspects of FLP design .......................................................................................... 40 Chapter 1. 5 - Frontiers and limitations of FLP chemistry ................................................................ 45 Chapter 1.5.1 - FLP-mediated hydrogenation of carbonyl compounds ....................................... 46 Chapter 1.5.2 - Moisture tolerance in FLP chemistry ................................................................... 47 Chapter 1.5.3 - Thesis aims .......................................................................................................... 48 Chapter 1.6 - References for Chapter 1 ........................................................................................... 49 Chapter 2 - Boron-based FLPs .............................................................................................................. 58 Chapter 2.1 - Introduction ............................................................................................................... 58 Chapter 2.2 - Catalytic
Load more

Recommended publications
  • NBO Applications, 2020
    NBO Bibliography 2020 2531 publications – Revised and compiled by Ariel Andrea on Aug. 9, 2021 Aarabi, M.; Gholami, S.; Grabowski, S. J. S-H ... O and O-H ... O Hydrogen Bonds-Comparison of Dimers of Thiocarboxylic and Carboxylic Acids Chemphyschem, (21): 1653-1664 2020. 10.1002/cphc.202000131 Aarthi, K. V.; Rajagopal, H.; Muthu, S.; Jayanthi, V.; Girija, R. Quantum chemical calculations, spectroscopic investigation and molecular docking analysis of 4-chloro- N-methylpyridine-2-carboxamide Journal of Molecular Structure, (1210) 2020. 10.1016/j.molstruc.2020.128053 Abad, N.; Lgaz, H.; Atioglu, Z.; Akkurt, M.; Mague, J. T.; Ali, I. H.; Chung, I. M.; Salghi, R.; Essassi, E.; Ramli, Y. Synthesis, crystal structure, hirshfeld surface analysis, DFT computations and molecular dynamics study of 2-(benzyloxy)-3-phenylquinoxaline Journal of Molecular Structure, (1221) 2020. 10.1016/j.molstruc.2020.128727 Abbenseth, J.; Wtjen, F.; Finger, M.; Schneider, S. The Metaphosphite (PO2-) Anion as a Ligand Angewandte Chemie-International Edition, (59): 23574-23578 2020. 10.1002/anie.202011750 Abbenseth, J.; Goicoechea, J. M. Recent developments in the chemistry of non-trigonal pnictogen pincer compounds: from bonding to catalysis Chemical Science, (11): 9728-9740 2020. 10.1039/d0sc03819a Abbenseth, J.; Schneider, S. A Terminal Chlorophosphinidene Complex Zeitschrift Fur Anorganische Und Allgemeine Chemie, (646): 565-569 2020. 10.1002/zaac.202000010 Abbiche, K.; Acharjee, N.; Salah, M.; Hilali, M.; Laknifli, A.; Komiha, N.; Marakchi, K. Unveiling the mechanism and selectivity of 3+2 cycloaddition reactions of benzonitrile oxide to ethyl trans-cinnamate, ethyl crotonate and trans-2-penten-1-ol through DFT analysis Journal of Molecular Modeling, (26) 2020.
    [Show full text]
  • A Germaaluminocene†
    Chemical Science View Article Online EDGE ARTICLE View Journal | View Issue A germaaluminocene† Cite this: Chem. Sci., 2020, 11, 2982 Lena Albers, * Patrik Tholen, Marc Schmidtmann and Thomas Muller¨ * All publication charges for this article The reactions of dipotassium germacyclopentadienediide with two Group 13 dichlorides, Cp*BCl and have been paid for by the Royal Society 2 * ff of Chemistry Cp AlCl2, yield two structurally di erent products. In the case of boron a borole complex of germanium(II) is obtained. The aluminium halide gives an unprecedented neutral Received 21st January 2020 Accepted 7th February 2020 germaaluminocene. Both compounds were fully characterised by multinuclear NMR spectroscopy supported by DFT computations. The molecular structure of the germaaluminocene was DOI: 10.1039/d0sc00401d determined by XRD. rsc.li/chemical-science Introduction conversion and aer work-up complex 2c was isolated as a brown oil in 35% yield (Scheme 2). NMR spectroscopy evi- The aim of utilizing readily available and environmentally denced the presence of the expected borole ring with a h1- benign main group element compounds for activation of bound cyclopentadienyl substituent. Interestingly, the NMR Creative Commons Attribution-NonCommercial 3.0 Unported Licence. unreactive materials and strong bonds instead of transition data indicated frozen rotation around the B-Ca single bond, metal-based complexes became increasingly popular during the giving rise to ten 13C NMR signals for the cyclopentadienyl last decade.1 We attempted to follow this lead by establishing substituent (Table S3, ESI†). In addition, all four carbon atoms polarised heteroalkenes I as they mimic the electronic situation of the borole ring are magnetically non-equivalent.
    [Show full text]
  • Parallels to Frustrated Lewis/Radical Pair Chemistry
    klh00 | ACSJCA | JCA11.2.5208/W Library-x64 | manuscript.3f (R5.0.i3:5004 | 2.1) 2020/02/05 13:43:00 | PROD-WS-121 | rq_481292 | 7/01/2020 12:12:45 | 10 | JCA-DEFAULT pubs.acs.org/IC Article 1 Redox-Controlled Reactivity at Boron: Parallels to Frustrated Lewis/ 2 Radical Pair Chemistry ⊥ ⊥ 3 Anthony Wong, Jiaxiang Chu, Guang Wu, Joshua Telser, Roman Dobrovetsky, and Gabriel Menard́ * Cite This: https://dx.doi.org/10.1021/acs.inorgchem.0c01464 Read Online ACCESS Metrics & More Article Recommendations *sı Supporting Information 4 ABSTRACT: We report the synthesis of new Lewis-acidic boranes μ 5 tethered to redox-active vanadium centers, (Ph2N)3V( -N)B(C6F5)2 μ 6 (1a)and(N(CH2CH2N(C6F5))3)V( -N)B(C6F5)2 (1b). Redox IV/V 7 control of the V couple resulted in switchable borane versus 8 “hidden” boron radical reactivity, mimicking frustrated Lewis versus 9 frustrated radical pair (FLP/FRP) chemistry, respectively. Whereas V 10 heterolytic FLP-type addition reactions were observed with the V 11 complex (1b) in the presence of a bulky phosphine, homolytic peroxide, IV 12 or Sn−hydride, bond cleavage reactions were observed with the V * μ 13 complex, [CoCp2 ][(N(CH2CH2N(C6F5))3)V( -N)B(C6F5)2](3b), 14 indicative of boron radical anion character. The extent of radical 15 character was probed by spectroscopic and computational means. IV/V 16 Together, these results demonstrate that control of the V oxidation 17 states allows these compounds to access reactivity observed in both FLP 18 and FRP chemistry.
    [Show full text]
  • Pentamethylcyclopentadienyl Aminoborole Complexes of Hafnium
    Pentamethylcyclopentadienyl Aminoborole Complexes of Hafnium Thesis by Andrew F. Kiely In Partial Fufillment of the Requirements for the Degree of Doctor of Philosophy Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena, California 1997 (Submitted August 20,1996) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. For M y Parents Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. iii Acknowledgments First and most importantly, I would like to thank John Bercaw for the support, encouragement, and opportunities that he has given me over the course of my studies at Caltech. I have been very fortunate to have been able to learn chemistry from someone who is a fine and generous person as well as a great scientist, and I am very grateful to him. I am also grateful to Bill Schaefer, Larry Henling, and Mike Day for performing all the crystallographic work that is reported in this thesis. I appreciate all their good humor and patience despite my (occasional) impatience and (more occasional) ignorance. I've really enjoyed hiking with Bill and playing outfield with Larry as well. The students and post-docs in the Bercaw group have been friends as well as coworkers. Over the years, people in the Bercaw group have been generous with their time, advice and friendship. When I was getting started in the group, Donny Cotter, Bryan Coughlin, and Roger Quan were never too busy to answer my questions or to set me straight. I'm especially grateful to Roger, who helped me to learn vacuum line techniques when I was starting on the aminoborole project.
    [Show full text]
  • The Water-Energy Nexus: Challenges and Opportunities Overview
    U.S. Department of Energy The Water-Energy Nexus: Challenges and Opportunities JUNE 2014 THIS PAGE INTENTIONALLY BLANK Table of Contents Foreword ................................................................................................................................................................... i Acknowledgements ............................................................................................................................................. iii Executive Summary.............................................................................................................................................. v Chapter 1. Introduction ...................................................................................................................................... 1 1.1 Background ................................................................................................................................................. 1 1.2 DOE’s Motivation and Role .................................................................................................................... 3 1.3 The DOE Approach ................................................................................................................................... 4 1.4 Opportunities ............................................................................................................................................. 4 References ..........................................................................................................................................................
    [Show full text]
  • Toward Thermodynamically Stable Triplet Carbenes Yumiao Ma* BSJ Institute, Haidian, Beijing, 100084 [email protected] Abstr
    Toward Thermodynamically Stable Triplet Carbenes Yumiao Ma* BSJ Institute, Haidian, Beijing, 100084 [email protected] Abstract In sharp contrast to the widely studied and applied stable singlet carbenes, only several kinetically persistent triplet carbenes have been studied, and thermodynamically stable triplet carbenes are much less developed. With the Gibbs free energy of C-H bond insertion into methane as a probe, DFT calculations were employed to examine a variety of candidate molecules for stable triplet carbenes. Guided by these calculations, some molecules with significant stability against C-H insertion were designed by fine tuning of geometry and electronic structures. These compounds might be potential candidates for experimental development of stable triplet carbenes. Introduction Pioneered by Guy Bertrand, Armin Arduengo and others, stable singlet carbenes have been well developed since 1980s1-3, and have exhibited great importance as ligands, reagents, etc. On the other hand, stable, or even kinetically persistent triplet carbenes are still scarce. A persistent triplet carbene, 2, 2', 4, 4', 6, 6'-hexabromodiphenylcarbene, was reported by Hideo Tomioka et al in 19954, with a half-life at ~1 s. In 2001, persistent triplet carbene with half-life of 19 min at room temperature was reported5, which was a great breakthrough. Several other kinetically persistent triplet carbenes were also studied, and the half-life ranges from microseconds to a week6, 7. However, thermodynamically stable triplet carbenes are still unknown hitherto, to the best of our knowledge. In this work, a variety of potential candidates for stable triplet carbenes were designed and examined by quantum chemical calculations. Guided by calculations and rational design, some competitive candidates were obtained, which may be helpful for the development of stable triplet carbenes, and for the understanding of the chemical properties related to open shell organic compounds.
    [Show full text]
  • The Reactivity of Hydrogen and Carbon Dioxide Mediated by Main Group Compounds
    THE REACTIVITY OF HYDROGEN AND CARBON DIOXIDE MEDIATED BY MAIN GROUP COMPOUNDS A dissertation submitted to Imperial College London for the degree of Doctor of Philosophy By Thomas James Herrington MChem (Oxon), Imperial College London May 2014 CID: 00467189 Supervised By Dr Andrew Ashley & Dr George Britovsek Chemistry Department 1 ABSTRACT The Reactivity of Hydrogen and Carbon Dioxide Mediated by Main Group Compounds The focus of this thesis has been the design and synthesis of new frustrated Lewis pair (FLP) systems which from structural modifications retain their ability to activate H2/CO2, while displaying differing reactivity modes. Chapter Two describes the first practical synthesis of tris[3,5- bis(trifluoromethyl)phenyl]borane (BArF18). Gutmann-Beckett Lewis acidity measurements reveal that this borane is a more powerful Lewis acid than B(C6F5)3, but it nevertheless is found to bind H2O much more reversibly than B(C6F5)3. The BArF18/2,2,6,6- tetramethylpiperidine (TMP) FLP provides a rare example of H2 activation in Et2O solvent, in which the borohydride salt has been structurally characterised by X-ray crystallography. A – novel bridging borohydride [-H(BArF18)2] was revealed, which contrasts to the characteristic terminal borohydrides formed by other borane based mediated FLP systems. Chapter Three details the design of fluorinated trisalkylboranes including B[CH(C6F5)2]3 which has been synthesised for the first time. This borane has been structurally characterised using X-ray crystallography and displays hydrogen bonding interactions between the ortho fluorines on each aryl ring and the adjacent CH proton. Interestingly, and despite this borane showing no Lewis acidity using Gutmann-Beckett and Childs techniques, the B[CH(C6F5)2]3/TMP FLP provides a rare example of H2 activation in THF solvent.
    [Show full text]
  • For Young Scientists
    THE BLAVATNIK AWARDS For Young Scientists N E R AT I O N O T G E F S C E X I E N N T E I F H I C T G I N I N N V O I V R A D T I O N 2021 The Blavatnik Awards for Young Scientists honor exceptional young scientists and engineers by celebrating their extraordinary achievements, recognizing outstanding promise, and accelerating innovation through unrestricted funding. Table of Contents Key Features ..............................................................................................................................................4 Our History ................................................................................................................................................6 Blavatnik Regional Awards ...................................................................................................................8 Blavatnik National Awards .................................................................................................................10 Blavatnik Awards in the United Kingdom ......................................................................................12 Blavatnik Awards in Israel................................................................................................................... 14 Blavatnik Science Scholars ................................................................................................................. 16 In the News ............................................................................................................................................. 18
    [Show full text]
  • Anew Drug Design Strategy in the Liht of Molecular Hybridization Concept
    www.ijcrt.org © 2020 IJCRT | Volume 8, Issue 12 December 2020 | ISSN: 2320-2882 “Drug Design strategy and chemical process maximization in the light of Molecular Hybridization Concept.” Subhasis Basu, Ph D Registration No: VB 1198 of 2018-2019. Department Of Chemistry, Visva-Bharati University A Draft Thesis is submitted for the partial fulfilment of PhD in Chemistry Thesis/Degree proceeding. DECLARATION I Certify that a. The Work contained in this thesis is original and has been done by me under the guidance of my supervisor. b. The work has not been submitted to any other Institute for any degree or diploma. c. I have followed the guidelines provided by the Institute in preparing the thesis. d. I have conformed to the norms and guidelines given in the Ethical Code of Conduct of the Institute. e. Whenever I have used materials (data, theoretical analysis, figures and text) from other sources, I have given due credit to them by citing them in the text of the thesis and giving their details in the references. Further, I have taken permission from the copyright owners of the sources, whenever necessary. IJCRT2012039 International Journal of Creative Research Thoughts (IJCRT) www.ijcrt.org 284 www.ijcrt.org © 2020 IJCRT | Volume 8, Issue 12 December 2020 | ISSN: 2320-2882 f. Whenever I have quoted written materials from other sources I have put them under quotation marks and given due credit to the sources by citing them and giving required details in the references. (Subhasis Basu) ACKNOWLEDGEMENT This preface is to extend an appreciation to all those individuals who with their generous co- operation guided us in every aspect to make this design and drawing successful.
    [Show full text]
  • Group 16 Elements in Frustrated Lewis Pair Chemistry
    Group 16 Elements in Frustrated Lewis Pair Chemistry by Fu An Tsao A thesis submitted in conformity with the requirements for the degree of Doctor of Philosophy Department of Chemistry University of Toronto © Copyright by Fu An Tsao 2018 Group 16 Elements in Frustrated Lewis Pair Chemistry Fu An Tsao Doctor of Philosophy Department of Chemistry University of Toronto 2018 Abstract Frustrated Lewis Pairs (FLPs) describe combinations of sterically encumbered Lewis acids and bases that do not form classical adducts. This unquenched reactivity has been shown to activate a wide plethora of small molecules, including H2, CO2, alkynes and ketones. While many different main group compounds have been applied in this context, studies of group 16 elements in FLP chemistry remain scarce. The main objective of this dissertation is to expand the scope of FLP chemistry to include group 16 elements, as they can function both as Lewis bases and as Lewis acids. The first portion of this dissertation focuses on the syntheses and reactivity studies of tellurium-boron heterocycles, wherein tellurium acts as a Lewis base. 1,1-carboboration of tellurium-substituted acetylides was shown to proceed smoothly at room temperature, leading to the formation of Te/B intramolecular FLP and 1,4-telluraborine. Several 1,4- telluraborines were found to have mild to high aromaticity as manifested by their unusual stability against oxygen and moisture. They can also undergo a number of unique reactions, including FLP-type alkyne exchange reactions and selective protonolysis of the exocyclic B–C bond. These findings allowed for the facile derivatization of this new class of compounds.
    [Show full text]
  • Sulfur Bonded Unsymmetrical Borole Complexes: Synthetic, Spectroscopic and Biocidal Aspects
    SULFUR BONDED UNSYMMETRICAL BOROLE COMPLEXES: SYNTHETIC, SPECTROSCOPIC AND BIOCIDAL ASPECTS Taruna Pandey1, V. P. Singh2 and R. V. Singh1* 1 Department of Chemistry, University of Rajasthan, Jaipur-302004, India 2 DSME, S.C.E.R.T., Varun Marg, Defence Colony, New Delhi-110024, India ABSTRACT Synthesis, characterization and biological activities of some of the unsymmetrical borole complexes containing B-S and B<-N bonds are described. The sulfur containing conjugated bases were prepared by the condensation of caibonyl compounds with thiosemicarbazide. The resulting complexes have been characterized by elemental analysis, molecular weight determinations and spectral studies including IR, Ή NMR, "Β NMR and ,3C NMR. The spectroscopic results showed that the conjugated bases behave in a bidentate fashion, whereas, the complexes display a tetracoordinated environment around the boron atom as steriochemically active lone pair is also included in the coordinated sphere. The conjugated bases and their respective boron complexes have been screened for their antifungal and antibacterial properties. INTRODUCTION Recently, few references on bidentate ligands coordinated to boron through the azomethine nitrogen and the thiolo sulfur have been published in the literature1·2. These compounds are interesting in many respects. Some have got a number of applications in industry, biology and agriculture. Industrial applications of coordination compounds of boron have remained fairly limited. Boron analogues of carboxylic acids and peptides have been shown to possess interesting biological activities in particular as serine protease inhibitors3. Use of boron-nitrogen compound in neutron capture therapy of brain tumors have also been investigated4. Several organoboranes find promising applications in the synthesis of insect pheromones5.
    [Show full text]
  • Issue 253 ▸ 1 November 2012 Reportersharing Stories of Imperial’S Community
    Issue 253 ▸ 1 November 2012 reporterSharing stories of Imperial’s community fringe benefits Visitors to the first Imperial Fringe take things to heart as they get to grips with our research → centre pages £35 MILLION FORWARD LONDON AWARD FOR THINKING BIKEATHON IMPERIAL Dr Simon Professor Dazzi HEFCE support Schultz on the on cycling 95 for Imperial value of looking miles with his West to the future patient PAGE 3 PAGE 7 PAGE 12 2 >> newsupdate www.imperial.ac.uk/reporter | reporter | 1 November 2012 • issue 253 Researchers unite to open up about animal research EDITOR’S CORNER Imperial has joined medical charities, remain high overall, with 66 per cent research funders, the pharmaceuti- of people supporting animal experi- cal industry and other universities mentation for medical research, Pregnant in signing a declaration for greater 40 per cent want to know more openness on animal research fol- before they form a firm opinion. pause lowing signs of a decrease in public Professor Maggie Dallman, “I hope this declaration will give s upport for animal research. Principal of the Faculty of Natural organisations and scientists the con- The results of a recent Ipsos Sciences, said: “Animal research fidence to speak out with the support As a number of you might Mori poll commissioned by the is a small but vital part of scientific of the wider research community.” know this is my final government reveal a 10 percentage and medical research in the UK. Ter- The declaration was signed by issue of Reporter before point decrease in public support for rorist activity by animal extremists in more than 40 research organisations, I go on maternity leave.
    [Show full text]