Different Strategies for Designing Dual-Catalytic Enantioselective Processes: From Fully Cooperative to Non-cooperative Systems.
Different Strategies for Designing Dual-Catalytic Enantioselective Processes: From Fully Cooperative to Non-cooperative Systems.
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DOI：
10.1021/jacs.9b05464
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发表时间：
2019-11
影响因子：
15
通讯作者：
Filippo Romiti;Juan del Pozo;Paulo H S Paioti;Stella A. Gonsales;Xinghan Li;Felix W W Hartrampf-Felix-W-W-Hartrampf-5045755;A. Hoveyda
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文献类型：
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作者：
Filippo Romiti;Juan del Pozo;Paulo H S Paioti;Stella A. Gonsales;Xinghan Li;Felix W W Hartrampf-Felix-W-W-Hartrampf-5045755;A. Hoveyda
化学研究的一个新兴领域要求我们学习如何管理一对助催化剂的特性，以便按照我们的意愿进行转化。在这些过程中，一种催化剂首先产生不可分离的中间体，然后在原位进行由不同催化剂促进的反应。此场景提出了几个设计问题。由于助催化剂通常具有重叠的功能，如果两种有机金属催化剂之间存在配体交换会怎样？我们如何确定助催化剂与特定的中间体发生特异性反应？如果反应性较低的助催化剂必须首先参与，而活性较高的助催化剂需要等待轮到它呢？我们该如何安排事件的正确顺序？虽然许多双催化工艺已经被引入，并且有评论，但仍有一些微妙而关键的区别属性尚未得到重视。虽然术语“双催化”和“协同催化”经常互换使用，但在许多情况下，催化剂并不完全协同。在这里，我们将讨论化学家如何能够协调催化剂的相反功能，以实现高效率和/或立体选择性。我们将表明，迄今为止所取得的进展可能是非正交多催化过程未来发展的序言（即，涉及几种催化剂的转化，这些催化剂本身并不协同），其中每种催化剂进入竞争的顺序将需要额外的创新策略。
An emerging area of research in chemistry requires that we learn how to manage the characteristics of a pair of co-catalysts so that a transformation proceeds as we wish it to. These are processes during which one catalyst first generates a non-isolable intermediate, which then in situ undergoes a reaction that is promoted by a different catalyst. This scenario raises several design issues. Since co-catalysts often have overlapping functions, what if there is an exchange of ligands between two organometallic catalysts? How can we be certain that a co-catalyst reacts specifically with a particular intermediate? What if the less reactive co-catalyst must engage first, and the one that is more active needs to wait its turn? How might we orchestrate the proper sequence of events? While many dual-catalytic processes have been introduced and reviews are available, there are subtle yet crucial distinguishing attributes that remain unappreciated. While the terms "dual-catalysis" and "cooperative catalysis" are often used interchangeably, on many occasions the catalysts are not entirely cooperative. Here, we will discuss how chemists have been able to harmonize the opposing functions of catalysts to achieve high efficiency and/or stereoselectivity. We will show that the progress achieved thus far is likely the preamble to the future development of non-orthogonal multi-catalytic processes (i.e., transformations involving several catalysts that are not inherently cooperative) where the order with which each catalyst enters the fray will demand additional innovative strategies.