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Experimental and computational studies towards chemoselective C-F functionalisation

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posted on 2022-08-01, 03:03 authored by Emily Jacobs

  

Cross-coupling reactions of organohalides with organometallic reagents offers a highly efficient modular approach to carbon-carbon bond formation, however limitations still exist in the scope of coupling partners. Organofluorides are particularly difficult to couple due to the strength of the C-F bond, however functionalization of C-F bonds under mild conditions could allow efficient late stage functionalisation of complex compounds. In addition, the unique reactivity of the metal-fluoride intermediate allows for base-free approaches and thus the potential for chemoselectivity, as other Ni-X species (X = Cl, Br, I) generated from oxidative addition to the metal centre would be unreactive.

As such, this work describes the development of a base-free Hiyama cross coupling reaction of 1-fluoronaphthalene and trimethoxy(phenyl)silane. After extensive screening and reaction optimisation, the coupling product was achieved in excellent yield under mild reaction conditions using a Ni(COD)2/PCy3 catalytic system. While control experiments with 1-chloronaphthalene highlighted the feasibility of the new chemoselectivity approach proposed in this Thesis, competition experiments with a mixture of 1-fluoronaphthalene and 1-chloronaphthalene failed to demonstrate the expected chemoselectivity. Density functional theory calculations were employed to gain mechanistic insight, as well as to provide some direction for the rational design of phosphine ligands to achieve chemoselectivity.

History

Table of Contents

Chapter 1: Introduction -- Chapter 2: Developing a system for C-F functionalisation using organosilanes -- Chapter 3: Density Functional Theorem for Mechanistic insights -- Chapter 4 : Future directions -- Chapter 5 : Conclusions -- Experimental section -- References

Notes

A thesis presented in partial fulfillment of the requirements for Masters of Research Includes bibliographical references (pages 49-59)

Awarding Institution

Macquarie University

Degree Type

Thesis MRes

Degree

Thesis MRes, Macquarie University, Department of Molecular Sciences, 2020

Department, Centre or School

Department of Molecular Sciences

Year of Award

2020

Principal Supervisor

Sinead Keaveney

Rights

Copyright disclaimer: https://www.mq.edu.au/copyright-disclaimer Copyright Emily Jacobs 2020.

Language

English

Extent

v, 59 pages

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