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Heterocyclic synthesis using amino acids
Abstract
A facile new method for the conversion of N-benzyloxycarbonyl-protected $\alpha$-amino acids to hydantoins by cyclization of the activated esters derived from Woodward's Reagent K is presented. The new cyclization proceeded with no observable racemization of chiral $\alpha$-amino acids. With a $\beta$-amino acid the method gave a pyrimidine-2,4-dione. Several alternative mechanisms by which this transformation might occur are described, one of which is preferred based on the experimental evidence available. Eight of the hydantoins synthesized using the new procedure were tested as potential anti-seizure drugs, but the compounds tested displayed little or no activity. The possible conversion of $\alpha$-amino acids to aziridinones ($\alpha$-lactams) is discussed. The X-ray crystal structure of 3-(4$\sp\prime$-bromophenyl)-1-tert-butylaziridinone is reported. The principal difference between the new crystal structure and the only previous X-ray crystal structure is the observation in the former of a distinct tilt of the lactam carbonyl group toward the nitrogen atom (and away from the $\alpha$-carbon atom), an observation that is in accord with most calculated structures for the aziridinone ring. The solid state structure suggests that $\alpha$-lactams exhibit considerable amide resonance. A careful nuclear magnetic resonance study of several typical aziridinones is described.
Subject Area
Organic chemistry
Recommended Citation
Eberspacher, Todd Alan, "Heterocyclic synthesis using amino acids" (1994). ETD collection for University of Nebraska-Lincoln. AAI9516580.
https://digitalcommons.unl.edu/dissertations/AAI9516580