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Design, Synthesis and Applications of Novel Hypervalent Iodine Reagents

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Design, Synthesis and Applications of Novel Hypervalent Iodine Reagents Design, Synthesis and Applications of Novel Hypervalent Iodine Reagents A Thesis Submitted to Cardiff University in Fulfilment of the Requirements for the Degree of Doctor of Philosophy by Jihan Qurban PhD Thesis July 2019 Cardiff University Jihan Qurban PhD Thesis 2019 __________________________________________________________________________________ DECLARATION This work has not been submitted in substance for any other degree or award at this or any other university or place of learning, nor is being submitted concurrently in candidature for any degree or other award. Signed …………………………… (Jihan Qurban) Date ………………….… STATEMENT 1 This thesis is being submitted in partial fulfillment of the requirements for the degree of ……………………… (insert MCh, MD, MPhil, PhD etc, as appropriate) Signed …………………………… (Jihan Qurban) Date ………………….… STATEMENT 2 This thesis is the result of my own independent work/investigation, except where otherwise stated, and the thesis has not been edited by a third party beyond what is permitted by Cardiff University’s Policy on the Use of Third-Party Editors by Research Degree Students. Other sources are acknowledged by explicit references. The views expressed are my own. Signed …………………………… (Jihan Qurban) Date ………………….… STATEMENT 3 I hereby give consent for my thesis, if accepted, to be available online in the University’s Open Access repository and for inter-library loan, and for the title and summary to be made available to outside organisations. Signed …………………………… (Jihan Qurban) Date ………………….… STATEMENT 4: PREVIOUSLY APPROVED BAR ON ACCESS I hereby give consent for my thesis, if accepted, to be available online in the University’s Open Access repository and for inter-library loans after expiry of a bar on access previously approved by the Academic Standards & Quality Committee. Signed …………………………… (Jihan Qurban) Date ………………….… ii Jihan Qurban PhD Thesis 2019 __________________________________________________________________________________ Acknowledgements Thanks for Allah the great for blessing me and giving me the power and persistence to complete my studies. Nobody can achieve any big goal without getting direct and indirect help and support. Doing a PhD is a milestone in my life, and I would not go through it without the help, support, kindness, time, and efforts of many people. The list is too long, but I will mention some people who had positively affected my research and my life during my PhD studies. First, my thanks and gratitude to my supervisor, Professor Thomas Wirth, not only for giving me the chance to join his outstanding research group and to work on such an interesting project, but also for the endless support, guidance, and fruitful discussions during all the stages of my PhD. For even criticism, which was always constructive and helped me to improve, acquire new expertise and develop my skills. Working with him was a real pleasure, he gave me the freedom to choose what is of interest for me, his patience and tolerance towards making mistakes and wrong decisions (sometimes), helped me to learn effectively and to build my personality. Next, I would like to express my thanks and dept to Dr Mohamed Elsherbini for his crucial role and impact on my research, for dedicating time for me, for the fruitful cooperation, for all the help he gave to me in and outside the lab. He was always there for me, answering my questions, correcting my mistakes, and encouraging me when I am down. His constant help, support, and his knowledge and kindness helped me to improve my skills and to trust myself. Thanks to all the people who were part of the Wirth research group, attended the group meetings and shared the office. Ana, Matt, Simon, Florence, Ravi, Anaïs, Célina, Adam, Rosaria, Agatha, Alex, Svenja, Tomohiro, Wilke, Xiaoping, Micol, Tobi, Filipa, Haifa, Mekhman, Ziyue, Mohamed, Marina, Tom, Rossana, Adele, Alena, Saira, Guilherme, Frauke, Nasser, Wenchao, Xiang-Yang, Abdul, Niklas, Taifur, Jarno, Paulina, Chrissi, Joey and James, without you all, without your suggestions, advice, support and company, my studies / life would be harder, less fun. My special gratitude to Ana, Flo, and Nasim for proof-reading parts of my thesis. Special thanks to Mohamed for proof-reading the whole thesis and for his advices and tips that helped me a lot during the writing up process. Thanks to my mentor and examiner Dr. Duncan Browne and Dr. Louis Morill for their valuable suggestions and all the guidance and support they gave to me. I would like to acknowledge all the technical and non-technical staff at the School of Chemistry (Cardiff University). Thanks iii Jihan Qurban PhD Thesis 2019 __________________________________________________________________________________ to Dr. Benson Kairuki (Cardiff University) for the X-Ray crystallographic analysis, and the EPSRC National Mass Spectrometry Service Centre (Swansea University) for their outstanding service providing mass spectrometric data. I would like to acknowledge the government of my country, and the University of Um-Alqura (Saudi Arabia) for the generous financial support, without which this work would not be possible. Finally, I would like to thank my loving husband and my lovely children for all the love, joy, and support they gave to me. Thanks to all my family and friends in Cardiff and in Saudi Arabia for their support, it would have never been the same without all of you. Special thanks to my parents, my sisters and brothers. Jihan Qurban iv Jihan Qurban PhD Thesis 2019 __________________________________________________________________________________ Dedicated to my small family: Mustafa, Aya, Abdulrahman, and Lin v Jihan Qurban PhD Thesis 2019 __________________________________________________________________________________ LIST OF ABBREVIATIONS °C Degree Celsius μL Microlitre Ac Acetyl AcOH Acetic acid A Amperes aq. Aqueous APCI Atmospheric pressure chemical ionisation Ar Aryl C Concentration Cat. Catalytic Conv. Conversion CV Cyclic voltammetry d.r. Diastereomeric ratio DBU 1,8-Diazabicycloundec-7-ene DIB (Diacetoxyiodo)benzene DCE 1,2-Dichloroethane DME 1,2-Dimethoxyethane DMF N,N-Dimethylformamide DMP Dess-Martin periodinane DMSO Dimethylsulfoxide EDG Electron donating group ee Enantiomeric excess EI Electron ionisation eq. Equivalent(s) ESI Electrospray ionisation Et Ethyl EWG Electron withdrawing group F mol-1 Faraday per mole FEP Fluorinated ethylene propylene g Gram GP General procedure GC Gas chromatography vi Jihan Qurban PhD Thesis 2019 __________________________________________________________________________________ h Hour(s) HFIP 1,1,1,3,3,3-Hexafluoro-2-propanol HOMO Highest occupied molecular orbital HPLC High pressure liquid chromatography HRMS High resolution mass spectroscopy Hz Hertz i-Pr Iso-Propyl IR Infrared J Coupling constant L Ligand LDA Lithium diisopropylamide LUMO Lowest unoccupied molecular orbital M Molarity [mol/l] mA milliamperes m.p. Melting point m/z Mass over charge ratio m-CPBA m-chloroperbenzoic acid Me Methyl Mes Mesityl MHz Megahertz min Minute(s) mL Millilitre mmol Millimole mol% Mole percentage N Normality nm nanometre n-BuLi n-butylllithium NMR Nuclear magnetic resonance psi Pounds per square inch p-TsOH p-Toluenesulfonic acid PEEK Polyether ether ketone PTFE Polytetrafluoroethylene Rf Retention factor (TLC) vii Jihan Qurban PhD Thesis 2019 __________________________________________________________________________________ rt Room temperature sat. Saturated t-Bu tert-butyl TEMPO 2,2,6,6-Tetramethylpiperidine 1-oxyl TfO Trifluoromethanesulfonate TFA Trifluoroacetic acid TFE 2,2,2-Trifluoroethanol TfOH Trifluoromethanesulfonic acid THF Tetrahydrofuran TLC Thin layer chromatography TMSOTf Trimethylsilyl trifluoromethanesulfonate Ts p-toluenesulfonyl vs versus V Volts viii Jihan Qurban PhD Thesis 2019 __________________________________________________________________________________ ABSTRACT Hypervalent iodine reagents are environmentally benign alternatives to heavy metal oxidants. They are widely used in organic synthesis not only because of the environmentally friendly nature but also due to their readily availability, selectivity and mild reaction conditions. Hypervalent iodine compounds are efficient reagents for a wide range of oxidative transformations such as oxidation of alcohols, phenol dearomatisation, functionalisation of carbonyl compound and alkenes, halogenation, oxidative heterocyclisation, and oxidative rearrangement reactions. In this thesis, novel electron-deficient chiral hypervalent iodine reagents have been designed and synthesised (Scheme i). The reactivity and selectivity of the newly synthesised reagents have been studied in several stereoselective oxidative transformations. Scheme i. Synthesis of novel electron-deficient lactate-based chiral iodine(III) reagents. Stereoselective oxidative rearrangement of alkenes into the corresponding α-aryl ketone (Scheme ii) was studied using chiral iodoarenes as organocatalysts. In addition, the same transformation was studied using electrochemically generated hypervalent iodine reagent. Scheme ii. Stereoselective oxidative rearrangement of alkenes. Finally, the design, synthesis, and characterisation of novel pseudocyclic hypervalent iodine reagents bearing heteroaryl carbonyl moieties is described (Scheme iii). The newly synthesised reagents showed similar and sometimes better reactivity than Koser’s reagent. Scheme iii. Synthesis of novel pseudocyclic hypervalent iodine reagents. ix Jihan Qurban PhD Thesis 2019 __________________________________________________________________________________
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