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Exploring new directions in hydrogen transfer chemistry

Polidano, Kurt 2019. Exploring new directions in hydrogen transfer chemistry. PhD Thesis, Cardiff University.
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Abstract

This thesis describes the development of new routes towards hydrogen transfer chemistry. Transfer hydrogenation is known concept in which hydrogen is transferred from one molecule to another without the use of molecular hydrogen. Borrowing hydrogen is a methodology which employs this concept and is known as hydrogen-autotransfer, as it combines a transfer hydrogenation process with a concurrent reaction on the in situ generated reactive intermediate. This is a great methodology as it doesn’t require toxic and harmful alkylating agents for alkylation. Alcohols are generally used for this methodology which are benign and friendly starting materials producing water as the sole by-product making this process highly atom economic. In this thesis, several methodologies related to hydrogen transfer chemistry have been developed. Initial research was focussed on tandem ruthenium catalysed hydrogen transfer and SNAr chemistry whereby sacrificial additives are used to facilitate the formation of two different sets of compounds following dehydrogenative SNAr chemistry. Several diaryl ethers and secondary amines are formed in good yields. The next project involved the development of a general iron-catalysed methylation using methanol as a C1 building block. The process exhibits a broad reaction scope with a variety of ketones, indoles, oxindoles, amines, and sulfonamides to undergo efficient methylation. This methodology was later applied to the β- methylation of alcohols which is described in a separate chapter in this thesis. The oxindole framework is present in several pharmacologically active compounds. Hence the next part of this thesis involved the development of an efficient iron-catalysed C(3)- alkylation of oxindoles via the borrowing hydrogen approach. This process exhibits a broad reaction scope, allowing primary and secondary aliphatic alcohols to be utilised as alkylating agents with a range of substituted oxindoles. Finally, the last chapter explains a one-pot ironcatalysed conversion of allylic alcohols to α-methyl ketones using methanol as C1 building block.

Item Type: Thesis (PhD)
Date Type: Completion
Status: Unpublished
Schools: Chemistry
Funders: EPSRC
Date of First Compliant Deposit: 25 February 2020
Last Modified: 25 Feb 2020 10:04
URI: http://orca.cf.ac.uk/id/eprint/129945

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