The ruthenium-catalyzed reduction and reductive n-alkylation of secondary Amides with hydrosilanes: Practical synthesis of secondary and tertiary amines by judicious choice of hydrosilanes
The ruthenium-catalyzed reduction and reductive n-alkylation of secondary Amides with hydrosilanes: Practical synthesis of secondary and tertiary amines by judicious choice of hydrosilanes
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DOI：
10.1021/jo070591c
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发表时间：
2007-09-28
影响因子：
3.6
通讯作者：
Nagashima, Hideo
中科院分区：
文献类型：
--
作者：
Hanada, Shiori;Ishida, Toshiki;Nagashima, Hideo
[图表]三钌簇（mu（3），eta（2），eta（3），eta（5）-苊烯）Ru-3（CO）（7）（1）催化仲酰胺与氢硅烷的反应，产生仲胺、叔胺和甲硅烷基烯胺的混合物。通过使用较高浓度的催化剂（3摩尔%）和使用双官能氢硅烷如1，1，3，3-四甲基二硅氧烷，实现了具有完全选择性的仲胺的生产。反应混合物的酸性后处理提供了相应的铵盐，其可以用碱处理，提供了用于分离高纯度仲胺的简便方法。相比之下，通过使用较低浓度的催化剂（1摩尔%）和聚合物氢硅氧烷（PMHS）作为还原剂，以高选择性形成叔胺。用PMHS还原将钌催化剂和有机副产物包封到不溶性有机硅树脂中。这两个反应歧管适用于各种仲酰胺，并且是实用的，因为该方法提供作为单一产物的所需仲胺或叔胺。该产品仅被极少量的钌和硅残留物污染。在产物和观察到的副产物以及NMR研究的基础上，还描述了反应的机理方案。
[GRAPHICS]A trituthenium cluster, (mu(3),eta(2),eta(3),eta(5)-acenaphthylene)Ru-3(CO)(7) (1) catalyzes the reaction of secondary amides with hydrosilanes, yielding a mixture of secondary amines, tertiary amines, and silyl enamines. Production of secondary amines with complete selectivity is achieved by the use of higher concentration of the catalyst (3 mol %) and the use of bifunctional hydrosilanes such as 1, 1,3,3-tetramethyldisiloxane. Acidic workup of the reaction mixture affords the corresponding ammonium salts, which can be treated with a base, providing a facile method for isolation of secondary amines with high purity. In contrast, tertiary amines are formed with high selectivity by using lower concentration of the catalyst (I mol %) and polymeric hydrosiloxanes (PMHS) as reducing agent. Reduction with PMHS encapsulates the ruthenium catalyst and organic byproducts to the insoluble silicone resin. The two reaction manifolds are applicable to various secondary amides and are practical in that the procedures provide the desired secondary or tertiary amine as a single product. The product contaminated with only minimal amounts of ruthenium and silicon residues. On the basis of the products and observed side products as well as NMR studies a mechanistic scenario for the reaction is also described.