Development of New Intramolecular Cyclization of Acetylenic Compounds for Materials Science

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The objective of this research was to develop new cyclization reactions of acetylenic compounds, which produce fundamental and important novel π-conjugated frameworks, and to open a new aspect in the organic electronics on the basis of this synthetic study. In this research, we particularly focus our attention on the ladder-type π-conjugated structures, and explored new synthetic methodologies for them. We have succeeded in the developments of several types of new reactions and have synthesized a series of important π-electron materials. Our achievements are summarized as follows.1. Reductive Bergman-type cyclization of diynes : Bergman cyclization is an example of the thermally-proceeding endo-endo mode cyclization of diynes. We have now succeeded in the development of an anionic version of this cyclization, i.e., endo-endo mode reductive cyclization using cyclic o-bis (silylethynyl) benzenes as the starting materials. This reaction will be useful for the functionalized acene synthesi … More s.2. Silicon/carbon-bridged oligo(p-phenylenevinylene)s : On the basis of an intramolecular reductive double cyclization of diphenylacetylene derivatives, we have succeeded in synthesizing a series of silaindene derivatives and silicon/carbon-bridged oligo(p-phenylenevinylene)s. The detailed study in their photophysical properties has revealed the effect of the silicon atoms on the excited state dynamics.3. Oligo(p-phenylenevinylene)s containing various main group elements : Silicon/sulfur-bridged distyrylbenzenes and group 15 element-bridged stilbenes have been synthesized based on the newly developed cascade-type anionic cyclization and one-pot intramolecular reductive cyclization, respectively, both of which shows unique fluorescence properties.4. Extended heteroacenes : We have developed a new intramolecular triple cyclization of diacetylenic compounds with sulfur to produce fused 1,2-dithiins. Combination of this methodology with the dechalcogenation produces a series of fused oligothiophenes. Their photophysical and electrochemical properties have been investigated to show their potentials as the materials for organic electronics, such as organic transistors. Less