Development of New icroencapsulated Polymer-Supported Catalysts

聚合物催化剂的效用现在是公认的，因为它们易于后处理和产物与催化剂的分离，从经济的角度来看，以及在工业过程中的应用等。然而，一般来说，聚合物催化剂具有一些缺点，例如难以制备、不稳定和低活性。为了解决这些问题，我们已经开发出了一种制备简单、活性高、可回收和重复使用的新型高分子催化剂--微胶囊催化剂。该催化剂很容易从四氧化锇和ABS聚合物的基础上的微胶囊技术制备。在大多数情况下，所需的二醇得到了高产率与高对映体过量。我们还开发了一种苯氧乙氧基甲基聚苯乙烯（PEM）为基础的新型聚合物负载的锇催化剂。该催化剂体系不需要缓慢加入烯烃，这是一个冗长的过程。催化剂可通过简单过滤定量回收，并可重复使用而不损失活性。虽然钯催化剂在有机合成中的各种转化中得到广泛应用，但它们价格昂贵，对空气敏感，并且在许多情况下无法回收。我们开发了三苯基膦钯，它已成功地用于几个钯催化反应。

The utility of polymer catalysts is now well-recognized because of their ease of workup and of separation of products and catalysts, from the economical point of view, and in application to industrial processes, etc. However, in general, polymer catalysts have some disadvantages such as difficult preparation, instability, and low activity. To address these issues, we have already developed new types polymer catalysts, named 'microencapsulated catalysts,' which are readily prepared, have high activity, and are recoverable and reusable.Catalytic asymmetric dihydroxylation of olefins using microencapsulated osmium tetroxide was developed. The catalyst was readily prepared from osmium tetroxide and an ABS polymer based on a microencapsulation technique. In most cases, the desired diols were obtained in high yields with high enantiomeric excesses.We have also developed a phenoxyethoxymethylpolystyrene (PEM)-based novel polymer-supported osmium catalyst. The catalyst system does not require a slow addition of olefins, which has been a tedious procedure. The catalyst was recovered quantitatively by simple filtration and reused without loss of activity.While palladium catalysts find wide-spread utility in a variety of transformations in organic synthesis, they are expensive, air-sensitive, and cannot be recovered in many cases. We have developed triphenylphosphine palladium, which has been successfully used in several palladium-catalyzed reactions.