针对以上三篇铁的催化反应，他们各有什么特点，有什么共同点以及各自的新颖的地方？阅读这类文献的时候，能给你什么启发？
另外，假如你的研究方向是做这类的，你如何寻求突破，而不是改一下配体结构，照虎画猫？
通过这些高质量的文章，可以修正一下自己的科研思维方式。
展开一点评述，什么是赶超世界一流，这个研究方向就是基础研究，有用吗？如果想做这个方向，能否超越，还是小打小闹？
创造世界一流大学，没有一流的研究团队去开创前沿课题，而是跟随，那怎么可能一流呢？
下面这篇由Crabtree写的评论（PDF格式见附件）值得一读。最后一段话：
This remarkable work is part of an emerging trend, in which different types of selective, catalytic C-H activation reactions are being successfully applied to more complex molecules than previously envisaged (4-6). With the conceptual barrier breached for hydroxylation, further striking applications to complex molecules are likely to emerge in the near future.
这就是时机，这就是赶超。面对这个问题，大家的起跑线都差不多。那么你准备好了怎么去竞争了吗？
Perspectives
[size=-1]CHEMISTRY:
No Protection Required
Robert H. Crabtree*
Organic synthesis has traditionally relied heavily on activating groups and protecting groups to steer synthetic reactions to the desired products. Activating groups such as halides enhance the reactivity of reactants, whereas protecting groups such as amides or esters block reactivity at undesired sites. On page 783 of this issue, Chen and White (
1) show that such activating and protection groups are not always required even in reactions involving complex molecules.
With the rise of green chemistry (
2), more attention is being paid to eliminating activating and protecting groups, wherever possible, for two reasons. First, they generate waste. Second, both activating and protecting groups require extra synthesis steps to be introduced into reactants; protecting groups also need extra steps to be removed after reaction. Catalysis can give reactivity and selectivity without the need for activating or protecting groups.The ideal catalyst reacts with an unactivated reactant with a selectivity that can be tuned by choice of catalyst. In practice, however, we are still far from the goal, particularly when the substrate is a complex organic molecule with multiple functional groups.
Perhaps the greatest challenge is finding catalysts that selectively attack C-H bonds, which are ubiquitous in organic compounds but are often very unreactive. A number of catalysts are known for this "C-H activation" reaction (
3), but they act only on simple molecules such as hydrocarbons. In more complex organic molecules, such as those commonly encountered in pharmaceuticals, numerous oxygen or nitrogen-containing functional groups are distributed over a core held together by carbon-carbon bonds. In such a polyfunctional molecule, unselective attack at any of a number of C-H bonds can result in a cocktail of final products.
Chen and White now report a striking counterexample that shows how C-H bonds can be activated selectively even in complex polyfunctional molecules (see the figure for an example). The authors used an iron catalyst to convert specific C-H bonds in a wide variety of molecules to C-OH groups; the benign and inexpensive hydrogen peroxide serves as the ultimate source of the oxygen atom.
| Selective conversion. The antimalarial compound artemisinin (below) is extracted from a shrub used in herbal form in Chinese traditional medicine. Although artemisinin has numerous C-H bonds and a delicate peroxide functional group, it gives a single product (right) when the Chen-White catalyst is used in conjunction with hydrogen peroxide. This implies that the catalyst has high selectivity even for a complex molecule, but predictability for other cases will require more detailed study. |
Depending on the specific case, the authors ascribe the remarkably high selectivity to a combination of a number of causes. These include the reactive C-H bond being either inherently more reactive than any other, or more physically accessible to the catalyst. The catalyst can also be attracted to a specific location by binding to a pre-existing functional group within the reactant, thus attacking only a nearby C-H bond. A goal in the area is to understand the relevant selectivity trends from the previous results, in order to predict the outcome in any subsequent case. Predictability is essential for the design of a multistep synthetic route relying on a selective, late-stage C-H activation, because failure at a later step would vitiate the entire scheme.
This remarkable work is part of an emerging trend, in which different types of selective, catalytic C-H activation reactions are being successfully applied to more complex molecules than previously envisaged (
4-
6). With the conceptual barrier breached for hydroxylation, further striking applications to complex molecules are likely to emerge in the near future.
References
- M. S. Chen, M. C. White, Science 318, 783 (2007).
- P. T. Anastas, M. M. Kirchhoff, Acc. Chem. Res. 35, 686 (2002).
- G. Dyker, Ed., Handbook of C-H Transformations (Wiley-VCH, Weinheim, 2005).
- A. R. Dick, M. S. Sanford, Tetrahedron 26, 2439 (2006).
- S. Das, C. D. Incarvito, R. H. Crabtree, G. W. Brudvig, Science 312, 1941 (2006).
- J. A. Labinger, J. E. Bercaw, Nature 417, 507 (2002).
10.1126/science.1150982 The author is in the Department of Chemistry, Yale University, New Haven, CT 06520, USA. E-mail:
robert.crabtree@yale.edu
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本帖最后由 agostic 于 2007-12-12 02:46 编辑 ]
