C–H-Activated Direct Arylation of Strong Benzothiadiazole and Quinoxaline-Based Electron Acceptors
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- 作者：Junxiang Zhang ; Timothy C. Parker ; Wayne Chen ; LaRita Williams ; Victor N. Khrustalev ; Evgheni V. Jucov ; Stephen Barlow ; Tatiana V. Timofeeva ; Seth R. Marder
- 刊名：Journal of Organic Chemistry
- 出版年：2016
- 出版时间：January 15, 2016
- 年：2016
- 卷：81
- 期：2
- 页码：360-370
- 全文大小：613K
- ISSN：1520-6904
文摘
Electron acceptors are important components of π-conjugated materials, but the strong electron-withdrawing properties of the required synthetic intermediates often make them poor substrates in synthetic schemes designed around conventional organometallic cross-coupling. Here, strong benzodiimine-based acceptors, including 5,6-difluoro[2,1,3]benzothiadiazole, 5,6-dicyano[2,1,3]benzothiadiazole, 5,6-dicyanobenzo[d][1,2,3]triazole, 6,7-dicyanoquinoxaline, and 6,7-dinitroquinoxaline, are shown to undergo facile palladium-catalyzed C–H direct arylation with a variety of bromoarenes in moderate to high yields. The electrochemical characteristics of di-2-thienyl derivatives synthesized using this methodology are compared and suggest that, in an electron-transfer sense, 5,6-dicyano[2,1,3]benzothiadiazole is a comparably strong acceptor to benzo[1,2-c:4,5-c′]bis[1,2,5]thiadiazole. The synthetic results suggest that high electron-withdrawing ability, which has traditionally limited reaction yields and structural variety in organic electronic materials, may be advantageous when employing C–H activated direct arylation in certain circumstances.