Efficient room-temperature alkyne metathesis with well-defined imidazolin-2-iminato tungsten alkylidyne complexes
Efficient room-temperature alkyne metathesis with well-defined imidazolin-2-iminato tungsten alkylidyne complexes
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DOI：
10.1002/anie.200703184
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发表时间：
2007-01-01
影响因子：
16.6
通讯作者：
Tamm, Matthias
中科院分区：
文献类型：
--
作者：
Beer, Stephan;Hrib, Cristian G.;Tamm, Matthias
烯烃复分解是一个卓越的有机金属成功故事，用于碳-碳双键断裂和形成的活性催化剂的开发对制备复杂天然产物和新材料的新方法的开发产生了巨大影响。[1，2]相关的炔的复分解反应代表了一种明显欠发达的合成方法，[3]尽管早在20世纪70年代中期就引入了第一个均相催化体系，例如[Mo（CO）6]和苯酚添加剂的混合物，以及在炔复分解反应中使用亚烷基络合物的概念。[4，5]迄今为止，仅已知有限数量的明确定义的次烷基络合物，其在其活性、底物相容性和所需反应温度方面满足对炔复分解催化剂的期望。[1a其中，新亚戊基络合物[Me 3CC W-（OCMe 3）3]代表用于诸如闭环炔复分解（RCAM）和炔交叉复分解（ACM）的应用的最广泛使用的钨基物质。[7]此外，已经建立了几种催化活性体系，其依赖于一般类型[Mo {N（tBu）Ar} 3]的钼（III）三酰氨基络合物的活化。[8]在此，我们介绍了一种新的设计策略的发展炔复分解催化剂。该方法利用了最具活性的烯烃复分解催化剂的结构，即I型稳定的钼和钨亚氨基烷叉基络合物（方案1）。最近，我们报道了III型单阴离子咪唑啉-2-亚氨基配体的制备，其可以通过两个限制共振结构IIIA和IIIB来描述，表明咪唑鎓环稳定正电荷的能力导致高度碱性配体[9]对早期过渡金属具有强的供电子能力。[10]由于它们作为2σ，4π-电子供体的能力，这些配体可以被认为是
Alkene metathesis is an organometallic success story par excellence, and the development of active catalysts for the breaking and making of carbon–carbon double bonds has had a tremendous impact on the development of new methods for the preparation of complex natural products and novel materials.[1, 2] The related metathesis of alkynes represents a significantly less-developed synthetic method,[3] although the first homogeneous catalytic systems, for example mixtures of [Mo (CO) 6] and phenol additives, and the concept of using alkylidyne complexes in alkyne metathesis were introduced as early as the mid 1970s.[4, 5]To date, only a limited number of well-defined alkylidyne complexes are known that fulfill the expectations for an alkyne metathesis catalyst with regard to its activity, substrate compatibility, and required reaction temperature.[1a, 3a, 6] Among these, the neopentylidyne complex [Me3CC W-(OCMe3) 3] represents the most widely used tungsten-based species for applications such as ring-closing alkyne metathesis (RCAM) and alkyne cross-metathesis (ACM).[7] Furthermore, several catalytically active systems have been established that rely on the activation of molybdenum (III) triamido complexes of the general type [Mo {N (tBu) Ar} 3].[8] Herein, we introduce a new design strategy for the development of alkyne metathesis catalysts. This approach draws on the structure of the most active alkene metathesis catalysts, stable molybdenum and tungsten imido alkylidene complexes of type I (Scheme 1). Recently, we reported the preparation of monoanionic imidazolin-2-iminato ligands of type III, which can be described by the two limiting resonance structures IIIA and IIIB, indicating that the ability of the imidazolium ring to stabilize a positive charge leads to highly basic ligands [9] with a strong electron-donating capacity towards early transition metals.[10] Owing to their ability to act as 2σ, 4π-electron donors, these ligands can be regarded as