Palladium-Catalyzed Miyaura Borylation of Overly Crowded Aryl Chlorides Enabled by a Complementary Localized/Remote Steric Bulk of Ligand Chassis
作者:Man Ho Tse、Rong-Lin Zhong、Fuk Yee Kwong
DOI:10.1021/acscatal.2c00263
日期:2022.3.18
the coupling processes employing highly sterically congested electrophilic partners have been a lasting challenge. Here, we report a general Pd-catalyzed Miyaura borylation of sterically hindered aryl chlorides. The key to the success of this reaction is the distinctive tailor-made phosphine ligand that features a smaller phosphine head and a larger remote steric bulk. This concept is, on the contrary
与使用特权底物的常见交叉偶联反应示例不同,使用高度空间拥挤的亲电伙伴的偶联过程一直是一个持久的挑战。在这里,我们报告了空间受阻芳基氯化物的一般 Pd 催化的 Miyaura 硼化。该反应成功的关键是独特的定制膦配体,其具有更小的膦头和更大的远程空间体积。相反,这一概念与常见膦的现有特性互补,例如 P t -Bu 3、联芳基-PCy 2等,其中它们由位于磷中心的局部空间体积组成。事实上,较小的膦基序有效地允许偶联伙伴在初始阶段接近 Pd 中心。我们的发现表明,即使是高度位阻的 2,6-二异丙基取代的芳基氯也适用于这种开发的催化剂体系。在这些反应条件下观察到良好的官能团相容性,并且对于特定的入口可以实现低至 0.05 mol% Pd 的催化剂负载。这种配体促成的 C-B 键形成的成功被认为为获得适合其他相关的高度空间位阻交叉偶联反应的催化剂建立提供了独特的基础知识。
Palladium-Catalyzed Direct Arylation of Polyfluoroarenes for Accessing Tetra-<i>ortho</i>-Substituted Biaryls: Buchwald-type Ligand Having Complementary −PPh<sub>2</sub> Moiety Exhibits Better Efficiency
作者:On Ying Yuen、Man Pan Leung、Chau Ming So、Raymond Wai-Yin Sun、Fuk Yee Kwong
DOI:10.1021/acs.joc.8b01176
日期:2018.8.17
The first general examples of direct C–H arylation of electron-deficient polyfluoroarenes with challenging di-ortho-substituted aryl(heteroaryl) chlorides for tetra-ortho-substituted biaryl synthesis are reported. Key to success is the use of Buchwald-type biaryl phosphine ligand, notably with inexpensive −PPh2 moiety (instead of −PCy2 group). Pd(OAc)2 associated with ligand L9 exhibits even higher