Magnetic CuFe2O4 Nanoparticles as an Efficient Catalyst for CO Cross‐Coupling of Phenols with Aryl Halides
Magnetic CuFe2O4 Nanoparticles as an Efficient Catalyst for CO Cross‐Coupling of Phenols with Aryl Halides
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DOI：
10.1002/cctc.201000254
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发表时间：
2011-01
期刊：
影响因子：
4.5
通讯作者：
Rongzhao Zhang;Jianming Liu;Shoufeng Wang;Jian-zhong Niu;C. Xia;Wei Sun
中科院分区：
文献类型：
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作者：
Rongzhao Zhang;Jianming Liu;Shoufeng Wang;Jian-zhong Niu;C. Xia;Wei Sun
二芳基醚是许多天然产物、工业聚合物和生物活性化合物中的重要结构基元。过渡金属催化的芳基卤化物和苯酚的偶联反应是制备二芳基醚的最直接的方法。钯催化合成二芳基醚的方法已经取得了很大进展。尽管钯催化方法的效率很高，但对昂贵的钯和复杂的配体的需求限制了其在大规模或工业规模生产中的应用。因此，成本较低的替代品仍然需求旺盛。铜介导的芳基卤化物和苯酚的偶联似乎是一种可选的方法，但它通常受到需要使用化学计量的铜和苛刻的反应条件的限制。因此，开发在相对温和的反应条件下制备二芳基醚的新方法正受到越来越多的关注。最近，Bolm和Taillefer基团开发了高效实用的铁催化剂，使各种二芳基醚的制备变得容易。5]2009年，Buchwald和Bolm发现铁催化剂的活性取决于金属盐的纯度。他们证明，在铁催化的CO交叉偶联反应中，仅存在10ppm的Cu2O就能显著提高产率。通过CO交叉偶联反应合成芳基醚的催化体系已有很多，但可重复使用的多相催化剂很少。作为我们正在进行的纳米颗粒催化剂制备研究的一部分，我们在此描述了纳米CuFe2O4作为一种可磁分离的催化剂用于酚和芳基卤化物的CO交叉反应(方案1)。据我们所知，这份报告首次将磁性纳米粒子用于苯酚和芳基卤化物的CO交叉偶联反应。根据文献，采用一种改进的方法制备了CuFe2O4纳米粒子(参见支持信息)。用粉末X-射线衍射法测定了CuFe2O4催化剂的结构，用X射线衍射法测定了催化剂的结构。
Diaryl ethers are important structural motifs in a large number of natural products, industrial polymers and biologically active compounds. Transitional metal-catalyzed coupling reactions of aryl halides and phenols are the most straightforward methods for the preparation of diaryl ethers. Much progress have been made in palladium-catalyzed methods for the synthesis of diaryl ethers. Despite the high efficiency of the Pd-catalyzed methods, the need for expensive palladium and elaborate ligands limits its application to largeor industrialscale production. Thus, less costly alternatives are still in high demand. The copper-mediated coupling of aryl halides and phenols appears to be a method of choice, but it is often limited by the need to employ stoichiometric amounts of copper and harsh reaction conditions. Therefore, development of new methods for preparation of diaryl ethers under relatively mild reaction conditions is receiving increasing interesting. Recently, the groups of Bolm and Taillefer developed efficient and practical iron catalysts that allow the easy preparation of a wide range of diaryl ethers. 5] In 2009, Buchwald and Bolm found that the iron catalyst activity depended on the metal salt purity. They demonstrated that the presence of only 10 ppm of Cu2O in the iron-catalyzed C O cross-coupling reaction led to a significant increase in the yield. Although many efficient catalytic systems for the synthesis of aryl ethers through C O cross-coupling reaction are well developed, few reusable heterogeneous catalysts have been employed in this reaction. As a part of our ongoing research into the preparation of nanoparticle-based catalysts, we describe herein the use of CuFe2O4 nanoparticles as a magnetically separable catalyst for the C O crossing reaction of phenols and aryl halides (Scheme 1). To our knowledge, this report represents the first use of magnetic nanoparticles for the C O cross-coupling reaction of phenols and aryl halides. CuFe2O4 nanoparticles were prepared with a modified method according to the literatures (see the Supporting Information). The structure of the CuFe2O4 catalyst was determined by powder X-ray diffraction (XRD; Figure 1), the diffraction