Synthesis of Bromo-, Boryl-, and Stannyl-Functionalized 1,2-Bis(trimethylsilyl)benzenes via Diels鈥揂lder or C鈥揌 Activation Reactions

详细信息    查看全文

• 作者：Christian Reus ; Nai-Wei Liu ; Michael Bolte ; Hans-Wolfram Lerner ; Matthias Wagner
• 刊名：The Journal of Organic Chemistry
• 出版年：2012
• 出版时间：April 6, 2012
• 年：2012
• 卷：77
• 期：7
• 页码：3518-3523
• 全文大小：324K
• 年卷期：v.77,no.7(April 6, 2012)
• ISSN：1520-6904

文摘

1,2-Bis(trimethylsilyl)benzenes are key starting materials for the synthesis of benzyne precursors, Lewis acid catalysts, and certain luminophores. We have developed efficient, high-yield routes to functionalized 4-R-1,2-bis(trimethylsilyl)benzenes, starting from either 1,2-bis(trimethylsilyl)acetylene/5-bromopyran-2-one (2) or 1,2-bis(trimethylsilyl)benzene (1)/bis(pinacolato)diborane. In the first reaction, 5 (R = Br) is obtained through a cobalt-catalyzed Diels鈥揂lder cycloaddition. The second reaction proceeds via iridium-mediated C鈥揌 activation and provides 8 (R = Bpin). Besides its use as a Suzuki reagent, compound 8 can be converted into 5 with CuBr₂ in i-PrOH/MeOH/H₂O. Lithium鈥揵romine exchange on 5, followed by the addition of Me₃SnCl, gives 10 (R = SnMe₃), which we have applied for Stille coupling reactions. A Pd-catalyzed C鈥揅 coupling reaction between 5 and 8 leads to the corresponding tetrasilylbiphenyl derivative. The bromo derivative 5 cleanly undergoes Suzuki reactions with electron-rich as well as electron-poor phenylboronic acids.