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Title: Claisen rearrangements of heterocycles
Author: Yow, Shu Hui
ISNI:       0000 0004 2716 7417
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2012
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This thesis is divided into five chapters. Chapter 1 is a review of de-aromatisation processes achieved by sigmatropic rearrangement. It covers the two main types of sigmatropic rearrangements, namely [2,3]- and [3,3]-rearrangement. Chapter 2 introduces the decarboxylative Claisen rearrangement (dCr) reaction and the aim to investigate its viability on more elaborate heterocyclic substrates is discussed. Research efforts into the synthesis of 3-sulfonyl-6-alkenyl-1,4-dioxan-2-ones are detailed. Chapter 3 discusses the extension of this methodology towards N-alkylmorpholinones. The first section examines 5,6-divinyl cis-morpholinones and L-alanine-derived trans-morpholinones as Claisen precursors, whereby stereospecific Ireland–Claisen rearrangement of L-alanine-derived trans-morpholinones was achieved. The second section details the synthesis of a novel L-proline-derived bicyclic morpholinone. However, attempted rearrangement led to degradation of product instead. The third section details the synthesis of 6-thienyl and 6-furanyl morpholinones, along with attempted Ireland–Claisen rearrangements and dCr reactions. Chapter 4 describes research efforts into the de-aromatising sigmatropic rearrangement of azide- and phthalimide-containing thienyl acyclic precursors. dCr Reaction of a cyanoacetate-containing substrate followed by unprecedented cyclisation led to the formation a highly-conjugated tetracycle and the mechanism of its formation is discussed. Chapter 5 provides experimental procedures and characterisation data.
Supervisor: Craig, Donald Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral