Electrochemical strategies for the generation and utilization of alkoxy radicals and alkene functionalization

Mishra, Deepak 2021. Electrochemical strategies for the generation and utilization of alkoxy radicals and alkene functionalization. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

This thesis describes the exploration and development of electrochemical methods for the generation and utilization of alkoxy radicals and alkene functionalization. Chapter 1 introduces the basic concepts of synthetic organic electrochemistry and also discusses some advanced analytical techniques employed in electrochemistry. Chapter 2 describes the manganese – catalyzed electrochemical deconstructive chlorination of cycloalkanols. After the initial proof-of-concept for the direct generation of alkoxy radicals by using tertiary alcohols (1-phenylcyclopropan-1-ol and 1- phenylcyclobutan-1-ol), mediated electrolysis is demonstrated using catalytic quantities of manganese(II) salts as a pre-catalyst to access active manganese(III) species, electrochemically. In total, 40 examples of various β and γ chlorinated ketones are reported. This transformation provides an advantage over other methods by excluding the necessity for chemical oxidant for the turning over of the catalyst. Chapter 3 addresses the limitation encountered in the preceding chapter. By leveraging the concept of Proton Coupled Electron Transfer (PCET), generation of alkoxy radical is achieved. Various triarylamine (Ar3N) are used as redox mediators for the homogeneous electron transfer to deconstructively synthesize distally brominated ketones starting from cycloalkanols. Furthermore, a single-pass continuous flow electrochemical scale-up is demonstrated at 10 mmol scale which showcases the efficient and robust scalability of the electrochemical process. And finally, chapter 4 discusses the electrochemical functionalization of alkenes. In the first part of the chapter, an interesting electrochemical trifluoromethylation of acrylamide is explored using Langlois’s reagent as a trifluoromethyl source. The second part of the chapter builds on a serendipitous discovery for the oxidative Z-selective (sp2)– H chlorination of acrylamides. The Z-selectivity is confirmed by x-ray crystallography and a radical clock experiment was employed to probe the mechanism of the transformation.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Chemistry
Date of First Compliant Deposit:	27 April 2022
Last Modified:	06 May 2023 02:31
URI:	https://orca.cardiff.ac.uk/id/eprint/149404

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