Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
J Am Chem Soc. 2010 Mar 31;132(12):4068-9. doi: 10.1021/ja1006405.
Selective methods for the functionalization of indoles and other nitrogen heterocycles would provide access to the core structures of many natural products and pharmaceuticals. Although there are many methods and strategies for the synthesis of substituted indoles or functionalization of the azole ring, strategies for the selective functionalization of the benzo-fused portion of the indole skeleton, particularly the 7-position, are less common. We report a one-pot, iridium-catalyzed, silyl-directed C-H borylation of indoles at the 7-position. This process occurs in high yield with a variety of substituted indoles, and conversions of the 7-borylindole products to 7-aryl-, 7-cinnamyl-, and 7-haloindoles are demonstrated. The Ir-catalyzed, silyl-directed C-H borylation also occurs with several other nitrogen heterocycles, including carbazole, phenothiazines, and tetrahydroquinoline. The utility of this methodology is highlighted by the one-pot synthesis of a member of the pyrrolophenanthridone class of alkaloid natural products.
选择性地对吲哚和其他氮杂环进行官能化，可以得到许多天然产物和药物的核心结构。尽管有许多方法和策略可以用来合成取代的吲哚或对唑环进行官能化，但是选择性地对吲哚骨架的苯并稠合部分（特别是 7 位）进行官能化的策略却较少见。我们报告了一种一锅法、铱催化、硅基导向的 C-H 硼化反应，可以在吲哚的 7 位进行。该过程在各种取代的吲哚中都能以高产率进行，并且可以将 7-硼基吲哚产物转化为 7-芳基、7-肉桂基和 7-卤代吲哚。该 Ir 催化的、硅基导向的 C-H 硼化反应也可以与其他几种氮杂环化合物一起发生，包括咔唑、吩噻嗪和四氢喹啉。该方法的实用性通过一锅法合成了一个吡咯并菲啶酮类生物碱天然产物的成员得到了突出体现。
