In the presence of palladium(II) acetate [Pd(OAc)2] and an N-heterocyclic carbene (NHC) ligand, fluorene derivatives can be generated in good to excellent yields from 2-halo-2′-methylbiaryls through the benzylic CH bond activation (14 examples; 81–97% yields). The scope and limitations of this protocol have been examined. A wide range of functional groups, such as alkyl, alkoxy, ester, nitrile, and
在乙酸钯(II)[Pd(OAc)2 ]和N-杂环卡宾(NHC)配体的存在下,芴衍生物可以从2-卤代2'-甲基联芳基通过苄基CH生成高至极好的收率键活化(14个例子;产率81-97%)。已经检查了该协议的范围和局限性。各种各样的官能团,例如烷基,烷氧基,酯,腈和其他,能够耐受本文的反应条件。同位素标记的联苯的环化反应产生相应的产物,具有主要的动力学同位素效应(k H / k D= 4.8∶1),这表明该反应的决定速率的步骤是苄基CH键的活化。此外,从三联苯中也获得了茚并芴的优异结果(3个实例;产率为91-92%)。2,6-二氯-2'-甲基联苯与二苯乙炔的级联反应通过芳基和苄基CH键的活化,以60%的收率产生了8,9-二苯基-4 H-环戊[ def ]菲。
Pd(OAc)2-catalyzed domino reactions of 1,2-dihaloarenes and 2-haloaryl arenesulfonates with Grignard reagents: efficient synthesis of substituted fluorenes
作者:Cheng-Guo Dong、Qiao-Sheng Hu
DOI:10.1016/j.tet.2008.01.020
日期:2008.3
suggested that Pd(leavinggroup)X associated arynes should be formed first and the sp(3) C-H activation preferentially occurred at benzylic C-(1 degrees )H bonds. The work described here provides a high yield, one-step access to substituted fluorenes from readily available 1,2-dihalobenzenes and 2-haloaryl arenesulfonates and hindered Grignard reagents, and this substituted fluorene-making method may find applications
Pd(OAc)<sub>2</sub>-Catalyzed Domino Reactions of 1-Chloro-2-haloarenes and 2-Haloaryl Tosylates with Hindered Grignard Reagents via Palladium-Associated Arynes
作者:Cheng-Guo Dong、Qiao-Sheng Hu
DOI:10.1021/ol061989i
日期:2006.10.1
The palladium-associated aryne generation strategy and Pd(OAc)(2)-catalyzed annulative Domino reactions of 1-chloro-2-halobenzenes and 2-haloaryl tosylates with hindered Grignardreagents via palladium-associated arynes are described. The palladium-associated aryne generation strategy described here not only allows the high yield, one-step access to potentially useful substituted fluorenes from readily