作者:Jeroen Wassenaar、Eveline Jansen、Willem-Jan van Zeist、F. Matthias Bickelhaupt、Maxime A. Siegler、Anthony L. Spek、Joost N. H. Reek
DOI:10.1038/nchem.614
日期:2010.5
The power of natural selection through survival of the fittest is nature's ultimate tool for the improvement and advancement of species. To apply this concept in catalyst development is attractive and may lead to more rapid discoveries of new catalysts for the synthesis of relevant targets, such as pharmaceuticals. Recent advances in ligand synthesis using combinatorial methods have allowed the generation of a great diversity of catalysts. However, selection methods are few in number. We introduce a new selection method that focuses on the stability of catalytic intermediates measured by mass spectrometry. The stability of the intermediate relates inversely to the reactivity of the catalyst, which forms the basis of a catalyst-screening protocol in which less-abundant species represent the most-active catalysts, âthe survival of the weakestâ. We demonstrate this concept in the palladium-catalysed allylic alkylation reaction using diphosphine and IndolPhos ligands and support our results with high-level density functional theory calculations. Identifying the best catalyst for a particular reaction traditionally involves testing a wide variety of metal and ligand combinations in standard reactions. Here, the best catalyst is found by using mass spectrometry to identify the least stable â and thus most reactive â intermediate in a dynamic mixture of complexes.
物竞天择、适者生存是大自然改良和提升物种的终极工具。将这一概念应用于催化剂开发具有很大的吸引力,可能会更快地发现用于合成药物等相关目标的新催化剂。近年来,利用组合方法进行配体合成的进展使得催化剂的多样性得以产生。然而,筛选方法却为数不多。我们介绍了一种新的筛选方法,该方法侧重于通过质谱测量催化中间体的稳定性。中间体的稳定性与催化剂的反应活性成反比,这构成了催化剂筛选方案的基础,其中含量较少的物种代表活性最强的催化剂,即 "弱者生存"。我们在使用二膦和吲哚磷配体催化的钯烯丙基烷基化反应中证明了这一概念,并用高水平密度泛函理论计算支持我们的结果。传统上,确定特定反应的最佳催化剂需要在标准反应中测试各种金属和配体组合。在这里,最佳催化剂是通过使用质谱法确定动态混合物中最不稳定的中间体,从而确定反应性最强的中间体。