Synthesis of Advanced Organic Materials with CH Substitution Reactions of Heteroaromatic Compounds

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C-H substitution reaction at the 5-position of thiophene was revealed to proceed with silver (I) nitrate and potassium fluoride as an activator. Addition of the activator in 2-5 portions drastically improved the yield of the coupling product.Cyclization precursors of intramolecular CH substitution reactions of nitrogen heteroaromatic compounds such as imidazoles and pyrroles were designed. The cyclization reaction enabled the formation of fused nitrogen heterocycles of complicated structre in a facile manner.In the combination of CH substitution reaction of heteroaromatic compound with coupling reaction of terminal alkynes with novel activators, which we developed recently, allowed the formation of 2, 5-diarylthiophenes and 2, 5-diarylthiazoles with alkyne spacer. Changes of spectroscopic properties of the produced compounds were discussed.With continueous homocoupling of thiophenes at the CH bond as a key reaction, well-defined oligothiophenes bearing 2-8 thiphene units were synthesized. Since the produced oligothiophenes possess carbon-bromine bond at the end thiophene ring, further modification with several functional groups were made possible. A transition metal-catalyzed coupling reaction furnished further functionalized oligothiophenes.