Use this URL to cite or link to this record in EThOS:
Title: Cinchona alkaloid-mediated asymmetric synthesis of amino acids and aziridines
Author: Jenner, Chloe Rachel
ISNI:       0000 0004 2676 8894
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2009
Availability of Full Text:
Access from EThOS:
Access from Institution:
In recent years the use of cinchona alkaloids as effective organocatalysts has been realised. The commercial availability and easy modification of these privileged structures establish them as attractive compounds for use in synthesis. For these reasons we were eager to apply cinchona alkaloid catalysis to the enantioselective synthesis of two important classes of molecule, p-amino acids and aziridines. (A) Synthesis of fi-Alkylaspartates via fi-Lactone Ring-Opening The cinchona alkaloid-catalysed reaction of ethyl glyoxylate with substituted ketenes, formed in situ from acid chloride precursors, gives as-disubstituted p-lactones in moderate yield and high enantiomeric excess. Glyoxylate has rarely been used in the amine-catalysed ketene cycloaddition and this chemistry allowed for the direct installation of an ester functionality into the product. Subsequent azide ring opening, reduction and ester hydrolysis allow access to chiral p-alkyl aspartates. (B) Synthesis of Aziridines from a,/J-Unsaturated Ketone Derivatives Our group has developed an organocatalytic reaction which furnishes unprotected aziridines in good yield from a,β-unsaturated ketone derivatives. Screening of chiral tertiary amines derived from the cinchona alkaloid motif allowed reasonable levels of enantioselectivity to be achieved. The substrate scope of the reaction was probed to incorporate a range of different alkene derivatives.
Supervisor: Armstrong, Alan Sponsor: EPSRC
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral