Doyle, Linda S.
NH-Isoxazolidines as Organocatalysts.
PhD thesis, National University of Ireland Maynooth.
This thesis describes the preparation and use of a range of N-unsubstituted bicyclic
isoxazolidines as potential organocatalysts in iminium ion and enamine catalysis.
The first chapter gives an overview of state-of-the-art organocatalysis. Reactions are
discussed in terms of the catalytic mechanism and a selection of reactions catalysed by
each route is included.
The second chapter discusses the design of two generations of N-unsubstituted
isoxazolidine frameworks as potential organocatalysts. The 1st generation, containing a
spirocyclohexane adjacent to the secondary amine of an isoxazolidine ring proved
difficult to prepare and debenzylation of the parent was problematic. The 2nd generation,
based on an isoxazolidine ring fused to a second heterocycle, were successfully
prepared and characterised by a combination of NMR spectroscopy, LC/TOF-MS,
microanalytical data and x-ray crystallography where necessary.
In the third chapter the application of NH-isoxazolidines as catalysts in the Diels-Alder
cycloaddition reaction, the Michael addition reaction and the Aldol condensation
reaction is discussed. It has been demonstrated that the NH-isoxazolidines are effective
in iminium ion catalysis and act as enantioselective organocatalysts for Diels-Alder
reactions. The aldol reaction between acetone and p-nitrobenzaldehyde could not be
promoted by the NH-isoxazolidines prepared in this thesis. Neither could these catalysts
promote the Michael addition reaction with trans-�-nitrostyrene and a minor amount of the Michael addition product was observed with 1,1-bis(benzenesulfonyl)ethylene as
The fourth chapter details the experimental procedures and full characterisation of all
new compounds described in this thesis.
The appendix carries details of the structures solved by x-ray crystallographic analysis
and as a representative a case full description of structural determination of a bicyclic
isoxazolidine is detailed.
Finally, a complete bibliography of articles referred to in this thesis is included.
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