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Title: Evaluation of asymmetric catalysts in C–C and C–N Michael type transformations
Author: Barron, Benedict James
ISNI:       0000 0004 6348 273X
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2017
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The first chapter of this thesis presents a literature survey of recent developments in asymmetric C–C and C–N conjugate addition reactions using metal mediated and organocatalytic protocols, focusing on the limitations and strengths of each system. The aim of this study will also be presented. The second chapter discusses the study of two asymmetric Pd (II) catalytic protocols in the aza-Michael reaction of N-containing arylamines with N-carbamates. The main body of work focuses on the utilisation of N-protected phenylenediamine substrates. In one case, these nucleophilic amines are poorly tolerated, with an interesting deactivation pathway uncovered. For the second protocol, high yields and ee are achieved with an interesting water effect observed. The afforded aza-adduct substrates were subsequently cyclised into tetrahydroquinoline derivatives, with particular attention paid to the regioselectivity of the transformation. This chapter also highlights the limitations of ortho-substituted anilines under these two protocols. The third chapter highlights the attempts to further extend these aza-Michael Pd(II) catalysed protocols to the reactions of substituted hydroxylamines with N-carbamates, with the overall objective of furnishing enantio-enriched aziridine products. Variation of the Michael acceptor was also explored, focusing on the utilisation of α-substituted α,β-unsaturated 1,3-dicarbonyls and alkylidene malonates in the aza-Michael addition with simple aniline derivatives. In the fourth chapter, Pd(II) catalytic protocols are applied to the asymmetric C–C Michael addition of β-ketoester and β-ketoamides to β-substituted α,β-unsaturated thioesters with little success. In contrast, the employment of an asymmetric MBI-derived phase transfer organocatalyst in the Michael addition of glycine Schiff base with various oxo and thio-ester Michael acceptors provided facile access to chiral γ-lactam derivatives. Chapter 5 contains experimental procedures and characterisation data for all synthesised compounds.
Supervisor: Hii, King Kuok (Mimi) Sponsor: Imperial College London
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral