| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2003: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2002: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Research Abstract |
Various derivatives of heteroaromatic compounds are known to exhibit pharmacological activities. Aryl-substituted heteroaromatics are of importance not only as medicinal agents, but also π-conjugated functional materials such as fluorescent dyes and organic semiconductors. Thus, the development of new, efficient methods for introducing aryl-substituent to heteroaromatics is an important subject. The objective of this project is to develop new protocols that are more general and efficient for the direct arylation of heteroaromatics by means of palladium-catalysis.
It was found that bulky tert-phosphines can effectively promote the reaction of thiophenes and thiazoles at the 2-and 5-positions. In some cases, copper(I) species acted as effective cocatalysts. Thiophenes having an electron-withdrawing group at the 3-position was observed to undergo arylation not only at 2-and 5 positions, but also at 4-position to give the triarylthiophene derivatives. Furthermore, it was discovered that 2-thiophenecarboxamides undergo triarylation accompanied by decarbamoylation to produce 2,3,5-triarylthhiophenes. This latter reaction could also be applied to the corresponding carboxamides of thiazole, furan, and oxazole. The optical properties of the above products were also measured. It was of significant interest that a bithiophene derivative having a considerable torsion in the molecule shows a fluorescent quantum yield more than 40%. During the performance this work, some other unique arylation reactions were also developed. The application of them will be investigated further.
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