Exploring the borrowing hydrogen methodology using earth abundant metals

Dambatta, Mubarak 2022. Exploring the borrowing hydrogen methodology using earth abundant metals. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

This thesis describes the development of new catalytic methodologies in borrowing hydrogen chemistry also known as hydrogen auto transfer, which is a sub-class of transfer hydrogenation chemistry. The main aim was to develop new catalytic methods via the borrowing hydrogen process using earth abundant metals like iron, mangane or cobalt. The second chapter of this thesis discusses the iron catalysed C(3)-alkylation of oxindole with alcohols via the borrowing hydrogen process using iron complex as the catalysts. Oxindole framework is found in many pharmacologically active compounds. It underwent selective C(3)- mono-alkylation with a wide range of simple aliphatic, benzylic and heteroaryl alcohols in good to excellent yield (28 examples, 79% average yield). The mechanistic study revealed the presence of reactive carbonyl intermediate and a metal hydride probing the borrowing catalytic process. In chapter three, the first transition metal C-alkylation of aryl ketones with secondary alcohols using only base was discussed. The method employed a bulky and sterically hindered substrate as the ketone, establishing a route for the synthesis of β-substituted carbonyl compounds with different secondary alcohols, giving a wide range of products with good yield (23 examples, 65% average yield). From the mechanistic study it was proposed that the reaction proceeds via an oppenauer-type oxidation of secondary alcohol followed by selective cross aldol�condensation and then the subsequent Meerwein-ponndorf-Verley (MPV)-type reduction of the enone. In the final research chapter, chapter four, the enantioselective N-alkylation of amines with secondary alcohols was investigated and the desired products was obtained in an excellent yield albeit with no any e.e vi and the isomerization/alkylation reaction of epoxy styrene with primary alcohols was also investigated but no any meaningful results was obtained from the pilot study.

Item Type:	Thesis (PhD)
Status:	Unpublished
Schools:	Chemistry
Date of First Compliant Deposit:	22 December 2022
Last Modified:	22 Dec 2023 02:30
URI:	https://orca.cardiff.ac.uk/id/eprint/155123

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