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Application of the Stereodivergent Oxy-Michael Cyclisation to the Synthesis of Natural Products and Organocatalytic Asymmetric Aldol Reactions in Water

Hsiao, Yin-Ting (2017) Application of the Stereodivergent Oxy-Michael Cyclisation to the Synthesis of Natural Products and Organocatalytic Asymmetric Aldol Reactions in Water. PhD thesis, University of York.

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Abstract

This work outlines two different projects. The first project was the study of a stereodivergent oxy-Michael cyclisation and its application towards the synthesis of natural products, diospongin A, diospongin B and psymberin/ircinistatin A. The α,β-unsaturated thioesters under TBAF-mediated conditions gave the 2,6-trans-tetrahydropyran; under acid-mediated conditions gave the 2,6-cis-tetrahydropyran. The 4-hydroxyl group is crucial for the stereodivergence; when the hydroxyl group was removed or protected the stereodivergence vanished. The second project was the study of (L)-proline benzyl ester-catalysed asymmetric aldol reactions in water. The reaction was carried out in a pH 7 buffered aqueous solution of cyclohexanone and a series of aryl aldehydes to provide anti aldol products in 7-89% ee. The aldol reaction between various ketone donors with 4-nitrobenzaldehyde under the same conditions were also developed to provide products in 13-61% ee.

Item Type: Thesis (PhD)
Related URLs:
Academic Units: The University of York > Chemistry (York)
Identification Number/EthosID: uk.bl.ethos.745741
Depositing User: Miss Yin-Ting Hsiao
Date Deposited: 11 Jun 2018 09:31
Last Modified: 24 Jul 2018 15:24
URI: http://etheses.whiterose.ac.uk/id/eprint/20324

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