Department of Chemistry and State Key Laboratory of Synthetic Chemistry , The Chinese University of Hong Kong , Shatin, N. T., Hong Kong , China.
J Am Chem Soc. 2019 Mar 13;141(10):4219-4224. doi: 10.1021/jacs.9b00302. Epub 2019 Feb 27.
A proof-of-concept example of catalytic regioselective cage B(8)-H functionalization of o-carboranes has been disclosed for the first time. Under the help of an acylamino directing group at cage B(3), a series of B(8)-arylated, B(4,7,8)-triarylated and B(4,7,8)-trifluorinated o-carborane derivatives were conveniently prepared. On the basis of isolation of a key intermediate, deuterium labeling experiments and DFT calculations, a reaction mechanism involving a high-valent palladium induced "cage-walking" from B(4) to B(8) vertex is proposed to account for the regioselective B(8)-H activation.
首次公开了一种 o--carboranes 笼 B(8)-H 催化区域选择性官能化的概念验证示例。在笼 B(3)上的酰氨基导向基团的帮助下，方便地制备了一系列 B(8)-芳基化、B(4,7,8)-三芳基化和 B(4,7,8)-三氟化 o-卡硼烷衍生物。基于关键中间体的分离、氘标记实验和 DFT 计算，提出了一种涉及高价钯诱导的从 B(4)到 B(8)顶点的“笼行走”的反应机制，以解释区域选择性的 B(8)-H 活化。
