Easily Attachable and Detachable ortho-Directing Agent for Arylboronic Acids in Ruthenium-Catalyzed Aromatic C-H Silylation
Easily Attachable and Detachable ortho-Directing Agent for Arylboronic Acids in Ruthenium-Catalyzed Aromatic C-H Silylation
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DOI：
10.1021/ja902314v
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发表时间：
2009-06-10
影响因子：
15
通讯作者：
Suginome, Michinori
中科院分区：
文献类型：
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作者：
Ihara, Hideki;Suginome, Michinori
以2-吡唑-5-苯胺为邻位定向剂，通过钌催化氢硅烷的硅化反应，使芳基硼酸的o-C-H硅化反应得以实现。本文原位制备了芳基硼酸与2-吡唑-5-苯基苯胺的缩合产物，并在135℃的条件下与三有机硅烷在RuH2(CO)(PPh3)(3)的存在下进行反应。邻位上的区域选择性硅基化反应对苯基硼酸产生了良好的收率，这些苯基硼酸含有氯、氟、甲基、甲氧基和三氟甲基等对取代基。对甲氧基羰基取代苯硼酸提供了相应的中等产量的硅基化产物。间甲基硼酸和2-萘硼酸在位阻较小的邻位上选择性地发生了硅基化。硅基化产物用于Suzuki-Miyaura偶联，然后用ICl碘化或Tamao氧化得到碘取代或羟基取代的双芳基。
o-C-H silylation of arylboronic acids has been achieved using 2-pyrazol-5-ylaniline as an ortho-directing agent, which was temporarily attached to the boronyl group via Ru-catalyzed silylation with hydrosilanes. Condensation products of arylboronic acids with 2-pyrazol-5-ylaniline were prepared in situ and subjected to reaction with triorganosilanes in the presence of RuH2(CO)(PPh3)(3) at 135 degrees C. Regioselective silylation at their ortho-positions proceeded in good yields for phenylboronic acids bearing para-substituents such as chloro, fluoro, methyl, methoxy, and trifluoromethyl groups. p-Methoxycarbonyl-substituted phenylboronic acid provided the corresponding silylated product in moderate yield. m-Tolyl- and 2-naphthylboronic acids underwent silylation selectively at the less sterically hindered ortho-positions. The silylated products were utilized in Suzuki-Miyaura coupling, followed either by iodination with ICl or by Tamao oxidation to furnish iodine- or hydroxy-substituted biaryls.