Optimized Synthesis, Structural Investigations, Ligand Tuning and Synthetic Evaluation of Silyloxy-Based Alkyne Metathesis Catalysts
作者:Johannes Heppekausen、Robert Stade、Azusa Kondoh、Günter Seidel、Richard Goddard、Alois Fürstner
DOI:10.1002/chem.201200621
日期:2012.8.13
groups have the advantage that they are more stable within the coordination sphere of a high‐valent molybdenum center than tert‐alkoxides, which commonly served as ancillary ligands in previous generations of alkyne metathesis catalysts. From a practical point of view it is important to note that complexes of the general type [(Ar3SiO)3MoX] (X = N, CR; R = aryl, alkyl, Ar = aryl) can be rendered air‐stable
具有三芳基硅烷醇酸酯配体的钼的氮化物和亚烷基络合物是各种炔烃复分解反应的极好(预)催化剂,因为它们结合了高活性和对极性和/或敏感官能团的出色耐受性。结构和反应性数据表明,这种有希望的应用前景是由于高价钼中心的特征与所选Ar 3 SiO基团的电子和空间特征之间的良好匹配而产生的。这种相互作用确保了中心原子上路易斯酸度的均衡水平,这对于高活性至关重要。此外,笨重的硅烷醇化物虽然不利于有效的亚烷基单元的双分子分解,但不会阻碍底物的结合。另外,Ar 3SiO基的优势在于,它们在高价钼中心的配位范围内比叔醇盐更稳定,后者在上一代炔烃复分解催化剂中通常用作辅助配体。从实际的角度来看是要注意的一般类型[(AR的该配合物是重要的3的SiO)3 MoX](X = N,CR; R =芳基,烷基中,Ar =芳基)可以呈现空气在1,10-菲咯啉,2,2'-联吡啶或其衍生物的帮助下稳定。尽管所得的加合物本身具有催