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Convertional methods for the synthesis of biaryl compounds Involve free radicals as intermediates and,in the case where unsymmetrLeal biaryls are desired,give rise to mixtures of products. A more elegant, and certainly more specific, approach would be to define the site oE substitution on the aryl substrate by suitably positioned electron-withdrawing substituents for attack by an aryl anion. Generation of the latter by using aryl lithium compounds, and their use as partners in coupling reactions with aryl halides formed the basis of this study. As the literature on organolithium chemistry is highly controversial and confusing, the present study initially involved a thorough investigation of the reactions of aryl halides with various organolithium reagents. It was found that the aryl halides could couple with themselves after metal - halogen exchange to give rise to biaryl and t n a r y 1 products. The reaction explored most fully was that between 2,4,6-tnbromophenol and methyl1ithium. The effects of varying the nature of the substituents and their position on the aromatic ring were also investigated. When the para substituents on a series of brominated phenol derivatives were varied through -F, -Cl, -Br, -H, am. -CH^, it was found that as the substituent became more electron-withdrawing the yield of biaryl product trom the reaction increased. In a parallel series of reactions, the hydioxyl group of the substrate was replaced by -OCH^, -CHj, -H and -Br. Biaryl products were then obtained only from those brominated aromatic compounds containing substituents capable of metal - hydrogen exchange. These results led to more specific reactions to clarify various points of mechanism and to the proposal that the aryl lithium species resulting from metal - halogen exchange may exist as dimers in solution. Two types of dimers are postulated to occi one type which collapses via an ionic pathway with elimination of lithium halide to form a biaryl product, and a second type of dimer which yields a biaryl product via a radical pathway with the concomitant and transient production of lithium metal. Evidence for the existence of both pathways is presented. Finally, applications of the results of this research were studied. Several avenues to the syntheris of a cannabinol analogue related to the constituents of Cannabis sativa were pursued but this target remained elusive. Other unsymmetrical biaryl compounds were howevei prepared in yields comparable to those quoted in the literature (usually by different methods) and a successful instance of "ionic " steering ot an ionic pathway for such a reaction was realized.

Thesis (Ph. D.)--Rutgers University, 2009. / "Graduate Program in Chemistry." Includes bibliographical references (p. 236-254).

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