## Doctoral Dissertations

Spring 1995

Dissertation

Chemistry

#### Degree Name

Doctor of Philosophy

Kenneth K Andersen

#### Abstract

The purpose of this research was to investigate routes towards the synthesis of $\alpha,\alpha\sp\prime$-dehydrodimeric amino acids. This dissertation describes various methods of effecting dehydrodimerization of bioxazoles. Bioxazoles are good candidates to serve as precursors to $\alpha\,\alpha\sp\prime$-dehydrodimeric amino acids, because they are $\alpha,\alpha\sp\prime$-dehydrodimeric amino acid derivatives. This dissertation describes the synthesis and characterization of d,l and meso 4,4$\sp\prime$-bioxazoles as well as, 2,4$\sp\prime$-bioxazoles.

A variety of bioxazoles were synthesized and some were subjected to nucleophilic ring opening. It had been reported that nucleophilic attack at the bioxazole ring caused the dehydrodimeric carbon-carbon bond to be cleaved. Results of this work indicate that cleavage is not a universal pathway in nucleophilic ring opening.

An attempt to complex a bioxazole with nickel bromide led to an investigation which proved that, at elevated temperatures, the bioxazole underwent a thermal isomerization. Though inclusive, investigation of the mechanism by EPR analysis indicated that the mechanism was radical based. A cross-over experiment confirmed that the mechanism of isomerization proceeded through a radical intermediate. Several bioxazoles and one bithiazole were heated in inhibitor free styrene to determine if bioxazoles would serve as a catalyst for radical polymerization. Though the cross-over experiment indicated that the bioxazoles fragmented into radicals at elevated temperatures, none of the bioxazoles heated in the presence of styrene induced polymerization.

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