Stereoselective alkene syntheses from cyclic enol ethers
Stereoselective alkene syntheses from cyclic enol ethers
Two novel methods for the stereoselective synthesis of trisubstituted olefins from cyclic enol ethers were investigated. The first utilised the nickel (O)-catalysed coupling reactions of α-alkyl substituted cyclic enol ethers with Grignard reagents. A study of the scope and limitations of such reactions was undertaken, employing substituted dihydrofurans as substrates. The reaction was shown to be of value for the efficient and stereoselective assembly of isoprenoid chains, and in a synthesis of the central C(8) to C(20) portion of pre-monensin B. Secondly, the discovery and development of a copper (I)-catalysed reaction of metallated cyclic enol ethers with organolithium reagents to yield functionalised alkenylcyanocuprates or alkenyllithium reagents are described. The reaction was found to be highly stereoselective and applicable to the synthesis of a range of unsaturated alcohols and some simple unsaturated spiroacetals. A reaction mechanism involving higher order cuprates, containing enol ethers as ligands, as the key intermediates is proposed.(DX86230)
University of Southampton
1988
Wadman, Sjoerd Nicolaas
(1988)
Stereoselective alkene syntheses from cyclic enol ethers.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Two novel methods for the stereoselective synthesis of trisubstituted olefins from cyclic enol ethers were investigated. The first utilised the nickel (O)-catalysed coupling reactions of α-alkyl substituted cyclic enol ethers with Grignard reagents. A study of the scope and limitations of such reactions was undertaken, employing substituted dihydrofurans as substrates. The reaction was shown to be of value for the efficient and stereoselective assembly of isoprenoid chains, and in a synthesis of the central C(8) to C(20) portion of pre-monensin B. Secondly, the discovery and development of a copper (I)-catalysed reaction of metallated cyclic enol ethers with organolithium reagents to yield functionalised alkenylcyanocuprates or alkenyllithium reagents are described. The reaction was found to be highly stereoselective and applicable to the synthesis of a range of unsaturated alcohols and some simple unsaturated spiroacetals. A reaction mechanism involving higher order cuprates, containing enol ethers as ligands, as the key intermediates is proposed.(DX86230)
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Published date: 1988
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Local EPrints ID: 460964
URI: http://eprints.soton.ac.uk/id/eprint/460964
PURE UUID: a220b9d7-53a1-475e-a7ff-05c0bbafcbbc
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Date deposited: 04 Jul 2022 18:32
Last modified: 04 Jul 2022 18:32
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Author:
Sjoerd Nicolaas Wadman
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