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Palladium-Catalyzed CH Arylation and Dehydrogenative Homocoupling of Heteroaromatic Compounds and Application to the Design of Advanced Organic Materials

2008; Oxford University Press; Volume: 81; Issue: 5 Linguagem: Inglês

10.1246/bcsj.81.548

1348-0634

Atsunori Mori, Atsushi Sugie,

Catalytic Alkyne Reactions

Abstract CH arylation of five-membered heteroaromatic compounds such as thiazoles and thiophenes recently developed by the authors is reviewed. The reaction of thiazole with aryl iodides in the presence of a palladium/copper catalyst system and tetrabutylammonium fluoride causes CH arylation at the 2-position of thiazole. The reaction of 2-arylthiazole with aryl iodide by the catalysis of a palladium complex with silver(I) fluoride induces CH arylation at the 5-position. The reactions allow preparation of a variety of 2,5-diarylthiazoles in a facile manner. Spectroscopic, thermal, and electrochemical characteristics of 2,5-diarylthiazole are summarized. Introduction of the 2,5-diarylthiazole moiety, which exhibits photoluminescent and liquid crystalline characteristics, into the side chain of polymethacrylate is also described. CH arylation of thiophene derivatives are described to occur similarly to the case of thiazole. CH homocoupling of thiophene leading to bithiophene, in which the carbon–bromine bond on the thiophene ring is completely intact in the palladium-catalyzed reaction, is also described. Mechanistic studies on the reactions of thiophene are shown with a stoichiometric use of arylpalladium(II) halide complex and thiophene to undergo electrophilic substitution at the thiphene ring toward the palladium atom and the following reductive elimination of the thus obtained aryl(thienyl)palladium complex.