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Title: Oxidative gold catalysis
Author: Ball, Liam Thomas
ISNI:       0000 0004 5354 700X
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2014
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The utility of aryltrimethylsilanes 1 as coupling partners in oxidative gold catalysis has been established through the development of first- and second-generation methodologies for alkene oxyarylation, and through the realisation of a protocol for the direct arylation of simple arenes. Oxidative oxyarylation of mono-substituted olefins 2 is achieved in the presence of a commercially-available precatalyst, Ph3P AuCl and a fluoronium oxidant, Selectfluor. The net addition of an O-nuc leophile and a silane-derived aryl moiety across the C=C double bond affords the conesponding homo benzylic alcohol derivative 3 with complete regioselectivity. Although diverse O-nucleophiles and arylating agents are tolerated, the substrate-scope is limited to alkenes bearing a single alkyl substituent due to the high reactivity of the oxidant. Relative to literature procedures employing arylboronic acids, the use of arylsilanes 1 significantly reduces the generation of symmetrical biaryls 4 via oxidative homocoupling of the arylating agent. Limitations imposed upon the first-generation protocol by Selectfluor prompted an extensive screen of reaction conditions that led to identification of l -hydroxy-I,2-benziodoxol-3-(lH)-one (IBA) as an efficient terminal oxidant for gold-catalysed oxyarylation. Use of IBA expands the substrate scope to include styrenes 5, thereby providing access to bibenzyls 6, and gem-disubstituted olefins 7, which afford tertiary homobenzylic alcohol derivatives 8. Whilst the range of suitable O-nucleophiles is largely resh'icted to methanol, sterically- and electronically-diverse arylsilanes 1 can be employed. Use of benzotrifluoride as the reaction solvent substantially reduces the generation of alylsilane homocoupling side-products 4.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available