## Doctoral Dissertations

Winter 1994

Dissertation

Chemistry

#### Degree Name

Doctor of Philosophy

Kenneth K Andersen

#### Abstract

A series of 4, 4$\sp\prime$-bisthiazolones have been synthesized. The study of the reactivities of these compounds was carried out in order to explore their use as possible precursors of dehydrodimeric amino acids, an almost unknown class of amino acids which might be the building blocks of cross-linked peptides. The synthesis of thiazolone monomers was achieved in several steps by using natural amino acids or their esters as starting materials. A new and efficient method has been developed to dehydrodimerize these monomers into bisthiazolones in high yield (more than 90% in many cases).

Theoretically, dimerization of thiazolones into the corresponding dimers through a radical mechanism could lead to 4, 4$\sp\prime$-dehydrodimers, 2, 4$\sp\prime$-dehydrodimers, and 2, 2$\sp\prime$-dehydrodimers. Thus, thiazolones with different substituents at 2 and 4 positions were synthesized in order to test the influence of electronic and steric effects on the ratios of these different dehydrodimers. The experimental results confirmed that both electronic and steric factors are important to the course of dehydrodimerization.

Reactivity studies were carried out on some of these 4, 4$\sp\prime$-bisthiazolones. The results showed that when bisthiazolones reacted with nucleophiles, the bond that joined the two thiazolones was preserved in some cases, but cleaved in others. Consequently, some derivatives of 4, 4$\sp\prime$-bisthiazolones were synthesized without cleavage of the 4, 4$\sp\prime$ carbon-carbon bond, which demonstrates the potential application of these bisthiazolones as precursors in the synthesis of dehydrodimeric amino acids and their derivatives.

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