The preparation of racemic and optically active beta-amino-acids and their utilisation in peptide formation.

B-Amino acids are being isolated from biologically active peptide antibiotics with increasing frequency nowadays. Recognition of the importance of these amino acids, has led to their incorporation into synthetic peptide analogues and into polymers. The main part of this thesis reports the successful preparation of linear and cyclic peptides of racemic and optically active B-aminobutyric acid. B-Amino acid cyclisation studies by Barker 84 had led to the conclusion that oxazinones could only be obtained from saturated B-benzamido—acids containing quaternary B-cabon atoms, while other saturated B-benzamido-acids (eg. B-aminobutyric acid) yield only symmetrical anhydrides. However, in this work oxazinones of both racemic and optically active B-aminobutyric acid were isolated, charaterised, and used as peptide coupling intermediates. A chiral oxazinone has thus been isolated for the first time, and used as a coupling intermediate 85 for the preparation of optically active peptides. Transacylation 89, of B-benzamidobutyric acid was encountered, during treatment of this compound with acetic anhydride under reflux conditions. While the use of isobutyl chloroformate allowed obtention of oxazinone in high yield at temperatures below-10°, its use at temperatures around 0° led to esterification of oxazinone by isobutyl alcohol. Arndt-Eistert Synthesis using N-tosyl derivatives led to the isolation of a chiral B-lactam during Wolff rearrangement in an inert solvent. Elsewhere in this thesis, it has been demonstrated that the formation of cyclohexylamide 89 as a side-product during peptide coupling of B-amino- pivalic acid with the acid of DCCI is due to alkaline cleavage of N-acylurea.

Name dc:type.qualificationname

PhD

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

Robert Gordon's Institute of Technology

Year dc:date.issued

1978

Author dc:creator

• Mtetwa, Eli

Advisor dc:contributor.advisor

• C.N.C. Drey

• B-amino acids
• Peptide antibiotics
• Cyclisation
• Arndt-Eistert synthesis
• Oxazinones
• Racemic
• Chiral
• Peptide coupling

Language dc:language

en

Identifier

oai:rgu-repository.worktribe.com:1993212
https://doi.org/10.48526/rgu-wt-1993212

OAI identifier oai:identifier

oai:rgu-repository.worktribe.com:1993212