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Applications of enzymes to the preparation of optically active compounds
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Opelt, Susan M. (1990) Applications of enzymes to the preparation of optically active compounds. PhD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b3226761~S15
Abstract
The introduction to this thesis is in the form of a review entitled 'Aspects of Selectivity in Lipase Catalysed Biotransformations'. Each of the most widely used lipases have been discussed. The reactions of each lipase have been extensively reviewed with the aim of establishing whether any trends have appeared in the characteristics of compounds accepted as substrates.
The remaining chapters cover five unrelated studies in areas of resolutions of chiral compounds using biotransformations. In Chapter 2 the resolution of a P-blocker precursor was attempted via lipase-catalysed hydrolysis. l-Chloro-2- hydroxy-3[4(2-acetoxyethyl) phenoxy] propane was obtained in high enantiomeric excess from hydrolysis of the corresponding butyrate ester with lipases from Mucor or Rhizopus sp. Yields were low however, owing to enzyme inhibition by the butyric acid byproduct.
In Chapter 3 the resolution of methyl 3-hydroxy-4-(p- chlorophenylthio)-butanoate was carried out. Hydrolysis of the corresponding butanoate ester with lipase P gave the R enantiomer of the desired compound in high enantiomeric excess. Transesterification of the racemic alcohol with vinyl acetate, again catalysed by lipase P, furnished the opposite enantiomer in 62%ee.
Chapter 4 is concerned with the resolution of a chiral acid, namely 3-methyl-4-oxo-4(4-aminobenzyl) butanoic acid. This was attempted by hydrolysis of an ester using pig liver esterase and various lipases and via microbial reduction of the corresponding unsaturated compound. The reactions were all found to be non-stereoselective.
Chapters 5 and 6 discuss novel methods for the enzymatic resolution of ketones.
The enantioselective enzymatic hydrolysis of oxime esters is discussed in Chapter 5. The resulting optically enriched oximes may readily be cleaved to the ketones. This method was unsuccessful in the resolution of the 2-methyl- and 2,6- dimethylcyclohexanones. A low enantiomeric excess was achieved in the resolution of norcamphor, and attempts to improve this using a purified enzyme and by variation of the ester chain were unsuccessful. However, this represents the first example of the indirect enzymatic resolution of ketones.
In Chapter 6 the enantioselective hydrolysis of enol acetates of three ketones was attempted. This method of resolution was unsuccessful in the resolution of 2-methyl and 2,6- dimethylcyclohexanones. In the case of norcamphor the ketone was obtained in low enantiomeric excess.
Item Type: | Thesis (PhD) | ||||
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Subjects: | Q Science > QD Chemistry Q Science > QP Physiology |
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Library of Congress Subject Headings (LCSH): | Lipase, Chromogenic compounds, Enzymatic analysis | ||||
Official Date: | October 1990 | ||||
Dates: |
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Institution: | University of Warwick | ||||
Theses Department: | Department of Chemistry | ||||
Thesis Type: | PhD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | Crout, D. H. G. | ||||
Sponsors: | Science and Engineering Research Council (Great Britain) ; Smithkline Beecham | ||||
Format of File: | |||||
Extent: | xv, 255 leaves : illustrations | ||||
Language: | eng |
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