Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.744718
Title: Photoredox C-C cross-coupling reactions using boronic acid derivatives
Author: Lima, Fabio
ISNI:       0000 0004 7228 5260
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2018
Availability of Full Text:
Access from EThOS:
Full text unavailable from EThOS. Please try the link below.
Access from Institution:
Abstract:
In recent years, photoredox catalysis emerged as a privileged tool for small molecules activation via single-electron transfer mechanisms. Despite their ubiquity as reagents in organic synthesis, the use of boronic acid derivatives to generate carbon-centred radicals remains elusive. This dissertation explores the utilisation of photoredox catalysis to generate carbon radicals from boronic acid derivatives and subsequently engage them in C–C cross-coupling reactions. In the first chapter, an introduction to photoredox catalysis and organoboron reagents is provided, as well as a discussion on the key mechanistic aspects of photoredox catalysed C–C cross-coupling reactions. The second chapter presents our initial coupling strategy and how it evolved in understanding that pinacol boronic ester species can be used as a source of carbon radicals via single-electron oxidation from a photoredox catalyst. Coordination of the boronic esters with Lewis basic species was identified as a fundamental activating interaction. The synthetic utility of this discovery was highlighted by performing a wide range of photoredox catalysed arylations of pinacol boronic esters. The third chapter builds on our mechanistic understanding to identify a set of Lewis base catalysts that conveniently activates boronic esters and acids towards single-electron oxidation. The usefulness of this improved set of conditions was demonstrated by alkylating a wide range of boronic acid derivatives. The fourth chapter describes the application of this methodology in synthesising four active pharmaceutical ingredients from the GABA family. An emphasis was made on developing an efficient flow process and “transition metal free” conditions to survey the attractiveness of the method for the pharmaceutical industry. Finally, the fifth chapter describes the experimental procedures relevant to the results described in chapters 2 to 4.
Supervisor: Ley, Steven Victor Sponsor: Novartis
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.744718  DOI:
Keywords: photoredox ; catalysis ; boronic acids ; boronic esters ; cross-couplings ; synthetic methods ; lewis base ; flow ; visible light ; photochemistry
Share: