| dc.description.abstract |
<p>A number of 4-hydroxy amino acids have been synthesized via 1,3-dipolar cycloadditions
of novel Z-nitrones and substituted olefins. Three achiral nitrones were synthesized
in pursuit of a conformationally stable yet reactive Z-nitrone. The carboisopropoxynitrone
was determined to be the best synthon in cycloadditions that favored a Z-nitrone oriented
transition state. Solvent studies were performed for cycloaddition reactions and it
was determined that polar solvents lead to "Z-derived" isoxazolidines whereas non-polar
solvents primarily afford "E-derived" isoxazolidines. The incorporation of MgBr<sub>2</sub>·OEt,<sub>2</sub>
to the reaction further enhanced the selectivity of the cycloaddition reaction in
favor of "Z-derived" intermediates.</p><p> Chiral carboisopropoxynitrone derivatives
were also realized and used in reactions with chiral olefins to afford optically active
4-hydroxy amino acids after several steps. (2R,4R) 4-hydroxyl-4-methylglutamic acid
and (2R,4R) Monatin were both synthesized in high purity from corresponding olefins
and the chiral carboisopropoxynitrone. Furthermore, the (2S,4S) enantiomers of both
amino acids could be synthesized via enantiomers of the chiral nitrone and olefins.</p>
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