A C–H Borylation Approach to Suzuki–Miyaura Coupling of Typically Unstable 2–Heteroaryl and Polyfluorophenyl Boronates
摘要:
A method for the synthesis of biaryls and heterobiaryls from arenes and haloarenes without the intermediacy of unstable boronic acids is described. Pinacol boronate esters that are analogous to unstable boronic acids are formed in high yield by iridium-catalyzed C-H borylation of heteroarenes and fluoroarenes. These boronates are stable in the solid state or in solution and can be generated and used in situ. They couple with aryl halides in the presence of simple palladium catalysts, providing a convenient route to biaryl and heteroaryl products that have been challenging to prepare via boronic acids.
An “On-Cycle” Precatalyst Enables Room-Temperature Polyfluoroarylation Using Sensitive Boronic Acids
作者:Liye Chen、Haydn Francis、Brad P. Carrow
DOI:10.1021/acscatal.8b00341
日期:2018.4.6
fluorinated arylboronic acid building blocks in cross-coupling has remained challenging, because of their acute base sensitivity. We report a general solution to this problem using a true catalytic intermediate, Pd(PAd3)(p-FC6H4)Br, as a uniquely effective “on-cycle” precatalyst that allows Suzuki–Miyaura coupling to occur much faster than even the most severe protodeboronation side reactions. Control of boron
交叉偶联中使用氟化芳基硼酸结构单元仍然具有挑战性,因为它们具有敏锐的碱敏感性。我们报告了使用真正的催化中间体Pd(PAd 3)(p -FC 6 H 4)Br作为唯一有效的“循环”预催化剂,可以使Suzuki-Miyaura偶联发生的速度快得多的一般解决方案。即使是最严重的原去硼副反应。还发现控制活性酸形式和休眠酯形式之间的硼形态在平衡催化速率与试剂分解之间起着至关重要的作用。该方法与任何氟化模式,对碱不稳定的官能团以及一系列溴(杂)芳烃均兼容。