Copper-Nitrene Complexes in Catalytic C-H Amination
Copper-Nitrene Complexes in Catalytic C-H Amination
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DOI：
10.1002/anie.200804304
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发表时间：
2008-01-01
影响因子：
16.6
通讯作者：
Warren, Timothy H.
中科院分区：
文献类型：
--
作者：
Badiei, Yosra M.;Dinescu, Adriana;Warren, Timothy H.
将典型的惰性碳-氢键直接催化转化为碳-氧、碳-氮和碳-碳键代表了有机合成和化学工业中的重大挑战。[1]理想地，这样的反应将不需要在化学转化过程中稍后被丢弃的官能团的存在，但是将以原子和能量效率进行并且具有最小的环境影响。能够直接促进这种转化的化学物质通常含有后过渡金属与氧、氮或碳中心之间的多个键。[2]自然界提供了酶的灵感，如细胞色素P-450，它能有效地通过铁-氧代中间体（[Fe]= O）将氧原子插入碳氢化合物的C2 H键中。[3]亚氨基碘烷（PhI= NR）的使用导致相关金属-氮烯中间体（[M]= NR）的产生，其在某些情况下表现出与碳-氢键的化学计量反应性以得到胺。[4]基于Rh、[5] Ru、[6] Ag、[7] Au、[8] Cu、[9]和其他金属的几种催化方案用于将苄基或烯丙基C13 H键与带有缺电子N取代基的亚氨基碘烷胺化，代表了将C13 H转化为C13 N键的有用方法。[2，10，11]在这些催化情况下，推断金属氮烯物种，但它们的高反应性使它们难以表征为活性中间体。在这种情况下，我们最近分离出一种双铜配合物[{（Me 3 NN）Cu} 2（μ-NAr）]（Ar= 3，5-二甲基苯基），其中氮烯结合在两个β-二酮亚胺铜片段之间。[12]溶液研究支持了末端铜氮烯[Cu]=[（Me 3 NN）Cu]通过从[{（Me 3 NN）Cu} 2（μ-NAr）]中解离出β-二酮亚胺铜片段而形成的中间体。由于不利的解离常数，不能直接观察到末端氮宾[Eq. (1);[Cu]=[（Me3NN）Cu]。
The direct catalytic transformation of typically inert carbon–hydrogen bonds into carbon–oxygen, carbon–nitrogen, and carbon–carbon bonds represents a significant challenge in organic synthesis and the chemical industry.[1] Ideally, such reactions would not require the presence of a functional group that is discarded later in the course of the chemical transformation, but would proceed with atom and energy efficiency and be of minimal environmental impact. Chemical species capable of directly promoting this transformation often contain multiple bonds between late transition metals to oxygen, nitrogen, or carbon centers.[2] Nature provides inspiration with enzymes such as cyctochrome P-450, which is efficient at inserting an oxygen atom into hydrocarbon CÀH bonds through an iron–oxo intermediate ([Fe]= O).[3] The use of iminoiodanes (PhI= NR) has led to the generation of related metal–nitrene intermediates ([M]= NR), which in certain cases, exhibit stoichiometric reactivity with carbon–hydrogen bonds to give amines.[4] Several catalytic protocols based on Rh,[5] Ru,[6] Ag,[7] Au,[8] Cu,[9] and other metals for the amination of benzylic or allylic CÀH bonds with iminoiodanes bearing electrondeficient N substituents represent useful methodologies for the transformation of CÀH into CÀN bonds.[2, 10, 11] In these catalytic cases, metal–nitrene species are inferred, but their high reactivity makes their characterization as the active intermediates difficult. This lack of characterization is unfortunate, as a fundamental understanding of metal–nitrene species that mediate catalytic CÀN bond formation would aid the development of more general systems for CÀH bond functionalization.In this context, we recently isolated a dicopper complex [{(Me3NN) Cu} 2 (μ-NAr)](Ar= 3, 5-dimethylphenyl) in which a nitrene is bound between two β-diketiminate copper fragments.[12] Solution studies supported the intermediacy of terminal copper–nitrene [Cu]=[(Me3NN) Cu] through the dissociation of a β-diketiminate copper fragment from [{(Me3NN) Cu} 2 (μ-NAr)]. The terminal nitrene could not be directly observed owing to an unfavorable dissociation constant [Eq.(1);[Cu]=[(Me3NN) Cu].