Iron-Catalyzed Dehydrogenative Coupling of Tertiary Silanes
Iron-Catalyzed Dehydrogenative Coupling of Tertiary Silanes
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DOI：
10.1002/anie.200805112
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发表时间：
2009-01-01
影响因子：
16.6
通讯作者：
Nakazawa, Hiroshi
中科院分区：
文献类型：
--
作者：
Itazaki, Masumi;Ueda, Kensuke;Nakazawa, Hiroshi
硅-硅键的形成是合成具有有趣的电子、光电和光反应性质的二硅烷、低聚硅烷和聚硅烷的重要步骤。一种广泛使用的方法是卤代硅烷在碱金属存在下的Wurtz型缩合。[1]然而，该常规方法具有若干缺点，包括苛刻的反应条件、副产物如二硅氧烷或聚硅氧烷（其中氧原子源自钠表面）的形成以及其不适用于官能硅化合物。过渡金属络合物也被用作催化剂以形成SiO2-Si键;[2-4]然而，在大多数情况下，只能使用第4、9和10族过渡金属的络合物。它们对伯硅烷和仲硅烷有效，但对叔硅烷活性低得多。[5]尽管开发了Zr、[6] Hf、[6] Ti/Zr、[7] Mn、[8] Rh、[9] Ir、[10] Pd、[11] Pt、[12]和Sm [13]催化剂，但仍然需要具有廉价和环境友好的催化剂的新方法。最近，我们发现在[CpFe（CO）2 Me]（Cp为η5-π）存在下，有机腈与HSiR 3反应中发生了催化的C3 CN键断裂和C3 Si键形成。[14]主要产物是甲硅烷基氰化物（R3 SiCN），但检测到痕量的乙硅烷（R3 SiR 3）。如果反应系统可以被改进以使乙硅烷成为主要产物，则该反应将以其低成本、容易获得的起始材料和铁络合物的环境友好特性以及对叔硅烷的适用性而区别。受到乙硅烷产物的形成的鼓舞，尽管仅为痕量，我们设想了铁催化剂在还原性SiO2-Si偶联反应中的应用[Eq.①]。
Silicon–silicon bond formation is an important step in the synthesis of disilanes, oligosilanes, and polysilanes with interesting electronic, optoelectronic, and photoreactive properties. One widely used method is the Wurtz-type condensation of halosilanes in the presence of alkali metals.[1] However, this conventional method has several drawbacks, including the harsh reaction conditions, the formation of by-products, such as di-or polysiloxanes (in which the oxygen atom stems from the sodium surface), and its inapplicability to functional silicon compounds. Transitionmetal complexes have also been used as catalysts to form SiÀ Si bonds;[2–4] however, in most cases only complexes of Group 4, 9, and 10 transition metals can be used. They are effective for primary and secondary silanes but are much less active with tertiary silanes.[5] Despite the development of Zr,[6] Hf,[6] Ti/Zr,[7] Mn,[8] Rh,[9] Ir,[10] Pd,[11] Pt,[12] and Sm [13] catalysts, the need remains for new methods with cheap and environmentally friendly catalysts. Recently, we found that catalytic CÀCN bond cleavage and CÀSi bond formation occurs in the reaction of organonitriles with HSiR3 in the presence of [CpFe (CO) 2Me](Cp stands for η5-cyclopentadienyl).[14] The main product was a silyl cyanide (R3SiCN), but a trace amount of a disilane (R3SiÀSiR3) was detected. If the reaction system could be modified to make the disilane become the main product, the reaction would be distinguished by its low cost, the ready availability of starting materials, and the environmentally benign character of the iron complex, in combination with applicability to tertiary silanes. Encouraged by the formation of the disilane product, although only a trace amount, we envisioned the application of iron catalysts in the dehydrogenative SiÀSi coupling reaction [Eq.(1)].