Highly conjugated, extended heterocycles are recognized as important materials for use in electronic applications, and therefore the synthesis and characterization of new molecules of this type are necessary. One method of forming extended heterocycles relies on the dual cyclizations of the hetero-ene-ene-yne motif. By controlling the reaction conditions, these systems can be made to selectively undergo either a pericyclic reaction to form a cinnoline or a coarctate cyclization to form an isoindazole. The ability of the hetero-ene-ene-yne motif to produce two different heterocycles with distinct properties makes it an attractive system to study. Another method of forming extended heterocycles with tunable properties is by fusing aromatic hydrocarbons with aromatic heterocycles such as thiophene. Chapter I introduces the coarctate reaction and gives an overview of the Haley lab's work in this area. Chapter II explores the dual cyclizations of a phenanthrene-based system. In Chapter III an anthraquinone-based cyclization precursor is used to make diazaheterocycle analogs of tetracene. In Chapter IV isoindazoles were joined by an ethynyl linker to either phenyltriazenes and phenyldiazenes to yield molecules that could undergo both coarctate ring-forming and coarcate ring-opening reactions. Chapter V presents the synthesis and characterization of a series of indacenedithiophenes. Chapter VI advances the synthetic methodology of making larger heteroacenes by presenting work toward heterocyclic pentacene analogs. This dissertation includes both previously published and unpublished co-authored material. / 10000-01-01