Diels-alder in aqueous molecular hosts: Unusual regioselectivity and efficient catalysis
Diels-alder in aqueous molecular hosts: Unusual regioselectivity and efficient catalysis
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DOI：
10.1126/science.1124985
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发表时间：
2006-04-14
期刊：
影响因子：
56.9
通讯作者：
Fujita, M
中科院分区：
文献类型：
--
作者：
Yoshizawa, M;Tamura, M;Fujita, M
自组装的空心分子结构作为介导化学反应的合成宿主很有吸引力。然而，产物结合抑制了这种系统的催化周转，而且选择性很少达到在结构更复杂的天然酶中观察到的水平。我们发现，在蒽和邻苯二甲酸亚胺的Diels-Alder偶联中，水相有机钯笼诱导了高度不寻常的区域选择性，促进了末端而不是中心蒽环的反应。此外，类似的碗形宿主在耦合相同底物时获得有效的催化转换（尽管使用传统的区域化学），很可能是因为产物的几何形状抑制了吸引平面试剂到宿主的芳香堆叠相互作用。
Self-assembled, hollow molecular structures are appealing as synthetic hosts for mediating chemical reactions. However, product binding has inhibited catalytic turnover in such systems, and selectivity has rarely approached the levels observed in more structurally elaborate natural enzymes. We found that an aqueous organopalladium cage induces highly unusual regioselectivity in the Diels-Alder coupling of anthracene and phthalimide guests, promoting reaction at a terminal rather than central anthracene ring. Moreover, a similar bowl-shaped host attains efficient catalytic turnover in coupling the same substrates ( although with the conventional regiochemistry), most likely because the product geometry inhibits the aromatic stacking interactions that attract the planar reagents to the host.