Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology , Av. Països Catalans 16, 43007 Tarragona, Spain.
ICREA , Passeig Lluïs Companys, 23, 08010 Barcelona, Spain.
J Am Chem Soc. 2017 Jan 25;139(3):1191-1197. doi: 10.1021/jacs.6b10998. Epub 2017 Jan 12.
Metal-catalyzed transformations that forge carbon-heteroatom bonds are of central importance in organic synthesis. Despite the formidable potential of aryl methyl ethers as coupling partners, the scarcity of metal-catalyzed C-heteroatom bond formations via C-OMe cleavage is striking, with isolated precedents requiring specialized, yet expensive, ligands, high temperatures, and π-extended backbones. We report an unprecedented catalytic ipso-silylation of aryl methyl ethers under mild conditions and without recourse to external ligands. The method is distinguished by its wide scope, which includes the use of benzyl methyl ethers, vinyl methyl ethers, and unbiased anisole derivatives, thus representing a significant step forward for designing new C-heteroatom bond formations via C-OMe scission. Applications of this transformation in orthogonal silylation techniques as well as in further derivatizations are also described. Preliminary mechanistic experiments suggest the intermediacy of Ni(0)-ate complexes, leaving some doubt that a canonical catalytic cycle consisting of an initial oxidative addition of the C-OMe bond to Ni(0) species comes into play.
金属催化的碳杂原子键形成转化在有机合成中具有核心重要性。尽管芳基甲基醚作为偶联伙伴具有巨大的潜力，但通过 C-OCH3 裂解形成金属催化的 C-杂原子键的情况却很少见，仅有的一些先例需要专门的、昂贵的配体、高温和π扩展骨架。我们报告了一种在温和条件下无需使用外部配体的芳基甲基醚的前所未有的 ipso-硅化催化反应。该方法的特点是其广泛的适用性，包括使用苄基甲基醚、乙烯基甲基醚和无偏苯甲醚衍生物，因此代表了通过 C-OCH3 断裂设计新的 C-杂原子键形成的重要进展。还描述了该转化在正交硅化技术中的应用以及进一步的衍生化。初步的机理实验表明 Ni(0)-ate 配合物的中间体，这使得人们对包含 C-OCH3 键与 Ni(0)物种初始氧化加成的典型催化循环是否起作用产生了一些疑问。
