A manganese catalyst for highly reactive yet chemoselective intramolecular C(sp(3))-H amination.
A manganese catalyst for highly reactive yet chemoselective intramolecular C(sp(3))-H amination.
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DOI：
10.1038/nchem.2366
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发表时间：
2015-12
期刊：
影响因子：
21.8
通讯作者：
Christina White M
中科院分区：
文献类型：
--
作者：
Paradine SM;Griffin JR;Zhao J;Petronico AL;Miller SM;Christina White M
C-H键氧化反应强调了现有的范例，其中高反应性和高选择性是负相关的。能够氧化强脂肪族C（sp3）-H键同时显示化学选择性（即耐受更多可氧化官能团）的催化剂的开发仍然是未解决的问题。在本文中，我们描述了一种催化剂，锰叔丁基酞菁[Mn（tBuPc）]，这是一个离群值的反应性-选择性范例。它的独特之处在于能够在分子内官能化所有类型的C（sp3）-H键，同时在π-官能度存在下显示出优异的化学选择性。机理研究表明，[Mn（tBuPc）]转移绑定氮烯的C（sp3）-H键之间的途径，位于协调C-H插入，观察与反应性贵金属（如铑），和逐步自由基C-H的提取/反弹，观察与化学选择性贱金属（如铁）。[Mn（tBuPc）]甚至胺化1°脂肪族和炔丙基C-H键，而不是实现效果的混合，反应性和选择性对于先前已知的催化剂是不寻常的。
C—H bond oxidation reactions underscore the existing paradigm wherein high reactivity and high selectivity are inversely correlated. The development of catalysts capable of oxidizing strong aliphatic C(sp3)—H bonds while displaying chemoselectivity (i.e. tolerance of more oxidizable functionality) remains an unsolved problem. Herein, we describe a catalyst, manganese tert-butylphthalocyanine [Mn(tBuPc)], that is an outlier to the reactivity-selectivity paradigm. It is unique in its capacity to functionalize all types of C(sp3)—H bonds intramolecularly, while displaying excellent chemoselectivity in the presence of π-functionality. Mechanistic studies indicate that [Mn(tBuPc)] transfers bound nitrenes to C(sp3)—H bonds via a pathway that lies between concerted C—H insertion, observed with reactive noble metals (e.g. rhodium), and stepwise radical C—H abstraction/rebound, observed with chemoselective base metals (e.g. iron). Rather than achieving a blending of effects, [Mn(tBuPc)] aminates even 1° aliphatic and propargylic C—H bonds, reactivity and selectivity unusual for previously known catalysts.