Computational Study of the Mechanism of Dehydrogenative Borylation of Terminal Alkynes by SiNN Iridium Complexes
Computational Study of the Mechanism of Dehydrogenative Borylation of Terminal Alkynes by SiNN Iridium Complexes
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DOI：
10.1021/acscatal.7b03835
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发表时间：
2018-01
期刊：
影响因子：
12.9
通讯作者：
Jia Zhou;Chun-I Lee;O. Ozerov
中科院分区：
文献类型：
--
作者：
Jia Zhou;Chun-I Lee;O. Ozerov
本文对SiNN钳形配体的Ir配合物催化端炔硼化反应的机理进行了全面的研究。本研究使用苯乙炔作为原型炔和频哪醇硼烷（HBpin）作为硼源。原始报告（J。Soc.2013，135，3560）在没有任何实质性证据的情况下提出了与通常归因于用于芳族C-H硼基化的Ir催化剂的机制类似的机制。然而，这项工作揭示了一个完全不同的机制图片。已经确定了三个相互关联的机制途径。的自由能垒位于约16-22千卡/摩尔的范围内，这是定性兼容的实验观察到的周转率的顺序为0.1 s-1。在所有这三种途径中的关键因素是Bpin基团在Ir和辅助SiNN配体的N（酰胺基）之间的容易迁移。特别是，迁移到N（氨基）的Bpin打开Ir中心的电子和CO2。
This paper presents a comprehensive study of the mechanism of dehydrogenative borylation of terminal alkynes (DHBTA) by Ir complexes of the SiNN pincer ligands. The study uses phenylacetylene as the prototypical alkyne and pinacolborane (HBpin) as the boron source. The original report (J. Am. Chem. Soc. 2013, 135, 3560) on this reactivity proposed, without any substantial evidence, a mechanism similar to that usually ascribed to Ir catalysts for aromatic C–H borylation. However, this work has uncovered a completely different mechanistic picture. Three interlinked mechanistic pathways have been identified. The free energy barriers lie in the range of approximately 16–22 kcal/mol, which is qualitatively compatible with the experimentally observed turnover rate on the order of 0.1 s–1. The key element in all three pathways is the facile migration of the Bpin group between Ir and the N(amido) of the ancillary SiNN ligand. In particular, migration of Bpin onto N(amido) opens the Ir center electronically and co...