Hallinan, Keith Oliver (1992) Synthetic and metabolic studies on [bēta],[gamma]-unsaturated [alpha]-amino acids. PhD thesis, University of Warwick.

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Abstract

(1) Chapter three describes the attempted investigation of the mechanism of cepham formation catalysed by the enzyme isopenicillin N synthase of Acremonium cephalosporium. The stereochemistry of this cyclisation was to be investigated with a specifically labelled butyrate residue in the unnatural substrate. 8-(a-amino) adipoyl-cysteinyl- a-aminobutyric acid. The chiral methyl and methylene groups were to be synthesised by the tritiation of specifically deuterated vinylglycine. This, in turn, was to be prepared from phenyl (2-lrimcthylsilylethynyl) sulphone. Scrambling of the deuterium labelling occurred in this synthesis of vinylglycine and so forced the abandonment of the experiment without concluding the investigation.

(2) Chapter four describes the preparation of vinylglycine in a simple,
inexpensive, three step synthesis. The synthetic pathway involved a Pinner reaction, sodium hypochlorite treatment and an aqueous Neber rearrangement. The overall yield was 52% from the vinylcyanide. This method was applied to the production of other b.y-unsaturated a-amino acids with mixed success. The resolution of the r-butyloxycarbonyI derivatives of the amino acids so prepared was investigated with the thiol protease, papain. Ethyl L-N-t-butyloxycarbonylvinylglycine prepared in this manner was transformed by epoxidation, dihydroxylation and cyclopropylation. An attempt to prepare a fluorothreonine derivative from the epoxide gave only the 2.3-dehydrohomoserine analogue.

(3) Chapter five describes the development of methyl (R)-(2-2H)- N-4-mcthoxyphcnylglycinatc (I) as a potential reagent for determining enantiomeric excess in chiral acids. The diastereomera formed differ only in isotopic stereochemistry, thus the possibility of kinetic resolution is reduced to a minimum. The ee is measured by the proton nmr spectrum of the diastereomera. In coupling (I) to a range of racemic chiral carboxylic acids the expected 1:1 ratio was observed. However during one of the steps in the preparation of (I) racemisation of the proton label occurred thus a single diastcrcomcr has yet to be prepared.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QD Chemistry Q Science > QP Physiology
Library of Congress Subject Headings (LCSH):	Stereochemistry
Official Date:	January 1992
Dates:	Date Event January 1992 UNSPECIFIED
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)
Format of File:	pdf
Extent:	viii, 166 leaves : illustrations
Language:	eng

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