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Construction and uses of chiral imidazolidin-2-ones in asymmetric synthesis
Doctoral Thesis   Open access

Construction and uses of chiral imidazolidin-2-ones in asymmetric synthesis

Sivakama Sundari Balasubramaniam
Doctor of Philosophy (PhD), Murdoch University
1998
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Abstract

Chiral auxiliaries and ligands form the basis of much of the modern developments in asymmetric synthesis. The recent literature has burgeoned with contributions in these two highly topical areas. The utility of the ephedrine and asparagine derived imidazolidin-2-one auxiliaries was the focus of this investigation. In certain respects, imidazolidin-2-ones represent a refinement of a number of earlier successful auxiliaries / ligands. In addition. they contribute some unique features to the methodology of asymmetric synthesis because of their generally higher crystallinity, resistance of the heterocycle to nucleophilic ring-opening, and their N-bifunctionality which permits their construction in C2-symmetric form. This project demonstrates the utility of the asparagine and ephedrine-derived imidazolidin- 2-ones as efficient chiral auxiliaries by, 1. Preparing new examples based on asparagine (i) and ephedrine (ii). 2. Exploitation of these compounds in a range of experiments involving, a) Diels-Alder reactions b) Aldol/Imine reactions. c) Addition to diethyl phosphite. The products of these reactions were readily purified by recrystallisation or chromatography. The diastereoselectivity ratios of the products were easily determined by HPLC orNMR.

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