Tetrakis(2-hydroxyphenyl)ethene and derivatives. A structurally preorganized tetradentate ligand system for polymetallic coordination chemistry and catalysis.
Tetrakis(2-hydroxyphenyl)ethene and derivatives. A structurally preorganized tetradentate ligand system for polymetallic coordination chemistry and catalysis.
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四(2-羟基苯基)乙烯及其衍生物。
DOI：
10.1021/ja027436u
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发表时间：
2002
影响因子：
15
通讯作者：
J. Stryker
中科院分区：
文献类型：
--
作者：
U. Verkerk;Megumi Fujita;Trevor L. Dzwiniel;R. McDonald;J. Stryker
发展了一种用于多金属配位化学的独特的、构象受限的四齿配体体系：四(2-羟基苯基)乙烯(1a)及其取代的衍生物。该设计利用四苯乙烯核的平面性为大致正方形的氧结合阵列赋予刚性，同时保持与芳基-乙烯碳-碳键旋转相关的一定程度的构象迁移率。四(2-羟基苯基)乙烯衍生物的设计目的是促进多金属桥联的配位模式。以苯甲醚或4-叔丁基苯甲醚为原料，通过2，2‘-二甲氧基二苯甲酮肼4a，b，分四步合成配体。通过用过氧化镍氧化原位生成的二芳基重氮甲烷，通过酸催化分解相应的二芳基重氮甲烷，高产率地生成空间受阻的邻位取代四亚乙基核。用三溴化硼去保护甲醚得到四(2-羟基苯基)乙烯(1a)和四(5-叔丁基-2-羟基苯基)乙烯(1b)。通过Claisen重排/氢化可以在3-位安装空间隔离取代基，有效地提供四(3-正丙基-2-羟基苯基)乙烯(6)。为了说明这类前所未有的配体的潜在应用，报道了两个配位化合物，包括四(2-二乙基铝氧基苯基)乙烯(8)，一个结构健壮的八元环铝氧冠合物，在溶液和固体中都具有特征。
A topologically unique, conformationally constrained tetradentate ligand system for polymetallic coordination chemistry has been developed: tetrakis(2-hydroxyphenyl)ethene (1a) and substituted derivatives. The design exploits the planarity of the tetraphenylethylene core to impart rigidity to the roughly square oxygen binding array, while maintaining a degree of conformational mobility associated with rotation about the aryl-ethylene carbon-carbon bonds. Tetrakis(2-hydroxyphenyl)ethene derivatives are designed to promote multiple metal bridging over chelating coordination modes. The ligand is synthesized from anisole or 4-tert-butylanisole in four steps via the 2,2'-dimethoxybenzophenone hydrazones 4a,b. The sterically hindered ortho-substituted tetraphenylethylene core is produced in high yield by acid-catalyzed decomposition of the corresponding diaryl diazomethane prepared in situ by oxidation of the hydrazone using nickel peroxide. Deprotection of the methyl ethers using boron tribromide gives tetrakis(2-hydroxyphenyl)ethene (1a), characterized by X-ray crystallography, and tetrakis(5-tert-butyl-2-hydroxyphenyl)ethene (1b). Sterically isolating substituents in the 3-position can be installed via Claisen rearrangement/hydrogenation, providing tetrakis(3-n-propyl-2-hydroxyphenyl)ethene (6) efficiently. To illustrate potential applications of this unprecedented ligand class, two coordination complexes are reported, including tetrakis(2-diethylaluminoxyphenyl)ethene (8), a structurally robust eight-membered-ring aluminum/oxygen crown complex characterized both in solution and in the solid state.