Copper(II) complexes of novel 1,5-diaza-cis-decalin diamine ligands:: An investigation of structure and reactivity
Copper(II) complexes of novel 1,5-diaza-cis-decalin diamine ligands:: An investigation of structure and reactivity
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DOI：
10.1021/om020425p
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发表时间：
2002-10-14
期刊：
影响因子：
2.8
通讯作者：
Xu, ZR
中科院分区：
文献类型：
--
作者：
Kozlowski, MC;Li, XL;Xu, ZR
1，5-二氮杂-顺式-十氢萘二胺的铜配合物在3-取代2-萘酚的氧化不对称联芳基偶联中是非常有效的。这些配合物作为催化剂的成功证明的基础上，已经作出了努力，以确定存在于反应中的铜物种，并构建合理的模型为假定的催化剂-底物络合物。本文报道了一系列1，5-二氮杂-顺式-十氢萘和N，N ′-二烷基-1，5-二氮杂-顺式-十氢萘Cu（Ⅱ）配合物的晶体结构。胺取代决定了形成的铜配位络合物的类型。对于仲胺化合物，1，5-二氮杂-顺式-十氢化萘，2：1二胺：铜络合物似乎是催化剂上有利的形式，但它们没有催化活性。还从1，5-二氮杂-顺式-十氢化萘产生催化活性的三聚1：1二胺：铜络合物的晶体，所述络合物含有桥连羟基。对于N，N '-二甲基-1，5-二氮杂-顺式-萘烷，形成1：1的二氨基外铜双-μ-羟基二聚体络合物。较大的N-烷基防止形成2：1二氨基外铜络合物以及二聚或三聚物质。例如，N，N ′-二乙基-1，5-二氮杂-顺式-萘烷形成单体1 ∶ 1二胺∶铜加合物。在这些结构的基础上，已经提出了一个模型的催化剂-底物复合物与观察到的对映选择性是一致的。在每个铜络合物中的二胺的绝对构型是相同的，即使当络合物是从外消旋二胺产生的，除了桥接二聚体。这一发现可以解释1，5-二氮杂-顺式-十氢萘铜配合物催化的不对称联芳基偶联反应中的非线性效应。
Copper complexes of 1,5-diaza-cis-decalin diamines are highly effective in the oxidative asymmetric biaryl couplings of 3-substituted 2-naphthols. On the basis of the demonstrated success of these complexes as catalysts, an effort has been made to identify the copper species present in the reaction and to construct plausible models for the presumed catalyst-substrate complexes. Crystal structures of a series of 1,5-diaza-cis-decalin and N,N'-dialkyl-1,5-diaza-cis-decalin Cu(II) complexes have been obtained. The amine substitution determines the type of copper coordination complex formed. For the secondary amine compound, 1,5-dia-za-cis-decalin, 2:1 diamine:copper complexes appear to be the thermodynamically favored forms, but they are not catalytically active. Crystals of a catalytically competent trimeric 1:1 diamine:copper complex containing bridging hydroxo groups were also generated from 1,5-diaza-cis-decalin. For N,N'-dimethyl-1,5-diaza-cis-decalin, a 1:1 diaminexopper bis-mu-hydroxo dimeric complex forms. Larger N-alkyl groups prevent formation of 2:1 diaminexopper complexes as well as dimeric or trimeric species. For instance, the N,N'-diethyl-1,5-diaza-cis-decalin forms a monomeric 1:1 diamine:copper adduct. On the basis of these structures a model of the catalyst-substrate complex has been proposed that is consistent with the observed enantioselection. The absolute configurations of the diamines in each copper complex were the same even when the complexes were generated from the racemic diamine, with the exception of the bridging dimer. This observation may serve to explain the nonlinear effects in the, asymmetric biaryl couplings catalyzed by the 1,5-diaza-cis-decalin copper complexes.