Synthesis of C2-Symmetric bisamidines:: A new type of chiral metal-free lewis acid analogue interacting with carbonyl groups
Synthesis of C2-Symmetric bisamidines:: A new type of chiral metal-free lewis acid analogue interacting with carbonyl groups
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DOI：
10.1021/jo070534j
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发表时间：
2007-07-20
影响因子：
3.6
通讯作者：
Goebel, Michael W.
中科院分区：
文献类型：
--
作者：
Akalay, Deniz;Duerner, Gerd;Goebel, Michael W.
从丙二腈出发，经两步反应制得手性双脒5。在单阳离子形式中，该化合物采用具有两个N-H基团的几乎会聚取向的平面构象。酮，醛，和硝基化合物被假定为通过氢键结合到这个强极性裂缝，导致在路易斯酸样活化的羰基。可以催化宽范围的反应（Diels-桤木、杂-Diels-桤木、Friedel-Crafts）。所观察到的加速超过率的影响，如硫脲或TADDOLs的中性氢键供体。
The chiral bisamidine 5 has been prepared in just two steps from malonodinitrile. In the monocationic form this compound adopts a planar conformation with an almost convergent orientation of two N-H groups. Ketones, aldehydes, and nitro compounds are assumed to bind to this strongly polar cleft via hydrogen bonds, resulting in a Lewis-acid-like activation of the carbonyl groups. A broad scope of reactions (Diels-Alder, hetero-Diels-Alder, Friedel-Crafts) can be catalyzed. The observed accelerations surpass the rate effects of neutral hydrogen-bond donors such as thioureas or TADDOLs.