NEW GREEN TECHNOLOGIES FOR ORGANOCATALYTIC ASYMMETRIC EPOXIDATION APPLICATIONS IN SYNTHESIS

Hassan, Noor (2014) NEW GREEN TECHNOLOGIES FOR ORGANOCATALYTIC ASYMMETRIC EPOXIDATION APPLICATIONS IN SYNTHESIS. Doctoral thesis, University of East Anglia.

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Abstract

This thesis describes the application of asymmetric epoxidation reactions on chromene
substrates mediated by Page’s iminium salt catalysts. Organocatalytic asymmetric
epoxidation is an efficient tool to access enantiomerically rich epoxides. This study is
divided into three main parts which are discussed in each chapter. The first part of this
research is the preparation of iminium salt catalysts followed by synthesis of several
chromene substrates. The final part is the application of the asymmetric epoxidation of the
readily prepared iminium salts on chromene substrates.
The first chapter reviews brief introduction and historical background of organocatalysis,
chromene substrates and asymmetric epoxidation reactions. Towards the end of the
chapter, several examples are described of past and current development of asymmetric
epoxidation by organocatalysts. In the last part of Chapter 1, the discussion focuses on
asymmetric epoxidation on chromene substrates. Chapter 2 discusses the preparation of
Page’s iminium salts and improvement of previous methods followed by several
approaches to synthesis of chromene substrates. The final part is discussing application of
asymmetric epoxidation using synthesized iminium salts on the chromene substrates.
Excellent enantioselectivities were observed in nonaqueous condition using TPPP as
oxidant for 6-cyano-2,2’-dimethylchromene giving ee >99% while reactions under aqueous
conditions afforded the corresponding diol giving ees as high as 71%.
In Chapter 3, experimental procedures and data for all the compounds synthesized are
included. Appendices contain HPLC trace data, NMR and IR data of several compounds.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Chemistry
Depositing User: Mia Reeves
Date Deposited: 09 Jul 2014 11:41
Last Modified: 09 Jul 2014 11:41
URI: https://ueaeprints.uea.ac.uk/id/eprint/49466
DOI:

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