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Biocatalytic asymmetric synthesis of biaryl atropisomers

Staniland, Samantha Louise

[Thesis]. Manchester, UK: The University of Manchester; 2016.

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Abstract

Biaryl atropisomers are common structural motifs in natural products but most importantly they are used as chiral ligands in asymmetric catalysis. Despite their utility, current methods to synthesise them are limited and lack generality. Often ligands such as QUINAP have to be synthesised as the racemate and are resolved using stoichiometric palladium which is expensive and time consuming. Biocatalytic synthesis of biaryl atropisomers offers a new alternative greener route to their production. A biocatalytic redox desymmetrisation of symmetrical biaryl diols using a mutant of galactose oxidase (M3-5) is reported. Desymmetrised biaryl atropisomers were produced in good to excellent ee and yield for a range of substrates. After the desymmetrisation a partial kinetic resolution increased the ee further as the minor enantiomer was converted to the dialdehyde. The first example of biocatalytic dynamic kinetic resolution to synthesise atropisomers asymmetrically has been developed. Freely rotating biaryl N-oxide aldehydes underwent reduction using a ketoreductase enzyme to give biaryl N-oxide products in excellent ee (96-99%). These products were found to be novel Lewis base organocatalysts for the asymmetric allylation of benzaldehyde derivatives.

Bibliographic metadata

Type of resource:
Content type:
Form of thesis:
Type of submission:
Degree type:
Doctor of Philosophy
Degree programme:
PhD Chemistry (48 month)
Publication date:
Location:
Manchester, UK
Total pages:
272
Abstract:
Biaryl atropisomers are common structural motifs in natural products but most importantly they are used as chiral ligands in asymmetric catalysis. Despite their utility, current methods to synthesise them are limited and lack generality. Often ligands such as QUINAP have to be synthesised as the racemate and are resolved using stoichiometric palladium which is expensive and time consuming. Biocatalytic synthesis of biaryl atropisomers offers a new alternative greener route to their production. A biocatalytic redox desymmetrisation of symmetrical biaryl diols using a mutant of galactose oxidase (M3-5) is reported. Desymmetrised biaryl atropisomers were produced in good to excellent ee and yield for a range of substrates. After the desymmetrisation a partial kinetic resolution increased the ee further as the minor enantiomer was converted to the dialdehyde. The first example of biocatalytic dynamic kinetic resolution to synthesise atropisomers asymmetrically has been developed. Freely rotating biaryl N-oxide aldehydes underwent reduction using a ketoreductase enzyme to give biaryl N-oxide products in excellent ee (96-99%). These products were found to be novel Lewis base organocatalysts for the asymmetric allylation of benzaldehyde derivatives.
Thesis main supervisor(s):
Thesis co-supervisor(s):
Language:
en

Institutional metadata

University researcher(s):

Record metadata

Manchester eScholar ID:
uk-ac-man-scw:297647
Created by:
Staniland, Samantha
Created:
22nd February, 2016, 20:03:01
Last modified by:
Staniland, Samantha
Last modified:
1st December, 2017, 09:08:47

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