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Investigations in combinatorial and solid phase organic chemistry

Investigations in combinatorial and solid phase organic chemistry
Investigations in combinatorial and solid phase organic chemistry

The insecticide industry faces increasing challenges from insect resistance to growing concerns over environmental issues. Synthesis of analogues of the insect moulting hormone, 20-hydroxyecdysone by solid phase methods was targeted as potential entry into new insecticide chemistry. The synthetic route utilised readily available 20-hydroxyecdysone that was converted by oxidative cleavage into poststerone that underwent solid phase attachment and either reductive amination or hydrazone formation. In the course of the reductive amination, a stereoselective reduction of the C20 ketone was used to generate dihydropoststerone. Synthesis of acetals on the 2,3 A-ring diol was carried out. Little biological activity over the native poststerone was identified.

Intermolecular radical additions to arenes are generally inefficient due to the large number of side products generated. Synthesis of three precursors for intramolecular radical addition of aryl radicals to arenes was accomplished. Two precursors were protected as model benzyl ethers and the third was immobilised on polystyrene resin. Each precursor underwent radical cyclisation and the results showed that solid phase immobilisation favoured intramolecular cyclisation over radical quench.

The use of high resolution Magic Angle Spinning (MAS) NMR to follow solid phase reactions was demonstrated. The preparation of resins loaded with the Wang linker and a short resin-based synthesis of alkenes was monitored by NMR.

University of Southampton
Wells, Neil James
Wells, Neil James

Wells, Neil James (2002) Investigations in combinatorial and solid phase organic chemistry. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

The insecticide industry faces increasing challenges from insect resistance to growing concerns over environmental issues. Synthesis of analogues of the insect moulting hormone, 20-hydroxyecdysone by solid phase methods was targeted as potential entry into new insecticide chemistry. The synthetic route utilised readily available 20-hydroxyecdysone that was converted by oxidative cleavage into poststerone that underwent solid phase attachment and either reductive amination or hydrazone formation. In the course of the reductive amination, a stereoselective reduction of the C20 ketone was used to generate dihydropoststerone. Synthesis of acetals on the 2,3 A-ring diol was carried out. Little biological activity over the native poststerone was identified.

Intermolecular radical additions to arenes are generally inefficient due to the large number of side products generated. Synthesis of three precursors for intramolecular radical addition of aryl radicals to arenes was accomplished. Two precursors were protected as model benzyl ethers and the third was immobilised on polystyrene resin. Each precursor underwent radical cyclisation and the results showed that solid phase immobilisation favoured intramolecular cyclisation over radical quench.

The use of high resolution Magic Angle Spinning (MAS) NMR to follow solid phase reactions was demonstrated. The preparation of resins loaded with the Wang linker and a short resin-based synthesis of alkenes was monitored by NMR.

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Published date: 2002

Identifiers

Local EPrints ID: 464895
URI: http://eprints.soton.ac.uk/id/eprint/464895
PURE UUID: 029879d1-6793-4edb-ae80-7ca954f7f870

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Date deposited: 05 Jul 2022 00:08
Last modified: 05 Jul 2022 03:29

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Author: Neil James Wells

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