Concave Reagents Based on Calixarenes
Concave Reagents Based on Calixarenes
复制标题
基于杯芳烃的凹面试剂
DOI：
10.1002/anie.199525551
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发表时间：
1995
影响因子：
--
通讯作者：
U. Lüning
中科院分区：
文献类型：
--
作者：
H. Ross;U. Lüning
酶的高（立体）选择性主要是由活性中心的凹环境引起的。相比之下。具有较简单结构的试剂表现出非选择性。根据凹面试剂的概念，标准试剂的选择性可以通过将它们放置在凹面环境中来改变。我的就像灯罩里的灯泡一样，凹面试剂的官能团被构建成一个双大环。凹型吡啶、邻菲咯啉等的合成路线多种多样。苯甲酸和硫代乙酸盐。[21具有官能团的单元，例如吡啶环，或者首先环化得到单大环，然后桥接形成双大环，或者在一锅反应中直接转化为双大环。经常是高稀释条件a;我们的目标是使用一种新的策略来合成凹型试剂：将容易获得的大环与含有官能团的结构单元桥接。杯芳烃非常适合于此目的，因为它们容易获得并且可以区域选择性地桥接。对叔丁基杯[4]芳烃（I）的桥连的实例已经知道相当长的时间。对叔丁基杯[6]芳烃（2）的桥连反应。[61通常，桥是柔性脂肪族链或聚醚链，或者它们是具有调整到杯芳烃1或2的几何形状的刚性单元。桥中的1 ′-酸性或碱性官能团是例外：已经合成了含有2.6-二茴香基吡啶桥的碱金属络合杯[4]芳烃。但它不是一种稠碱，因为它的吡啶氮原子从杯芳烃腔的外部比从杯芳烃腔的内部更容易接近。
The high (stereo) selectivity of an enzyme is mainly caused by the concave environment of the active site. In comparison. reagents with simpler structures behave unselectively. According to the concept of concave reagents, the selectivity of standard reagents can be altered by placing them in a concave enviroiiinent. l'.'l Like a light bulb in if lamp shade, the functional group of the concave reagent is built into a bimacrocycle. Vari-ous synthetic pathways are used to prepare concave pyridines, phenanthrolines. benzoic acids. and thiolacetates.[21 The unit with the functional group, for example a pyridine ring,"-31 is either first cyclized to give a monomacrocycle and then bridged to form a biinacrocycle, or it is converted directly into a bimacrocycle in a one-pot reaction. Often high-dilution conditiona; ire necesary.Our goal was to use a new strategy for the synthesis of concave reagents: An easily accessible macrocycle was to be bridged with; I building block that contained the functional group. Calixareiics'"] are well suited for this purpose because they are easily accessible and can be bridged regioselectively. Examples for the bridging ofp-/rrr-butylcalix [4] arene (I) have been known for quite soine time.[''and the bridging of the larger p-tcrf-butylcalix [6] arene (2) was reported recently.[61 Usually the bridges are either flexible aliphatic chains or polyether chains, or they; ire rigid units with geometries adjusted to the calixarenes 1 or 2. l'-Acidic or basic functional groups in the bridges are the exception: an alkali metal complexing calix [4] arene containing a 2.6-dianisylpyridine bridge has been synthesized.['] But it is not il concxvc base because its pyridine nitrogen atom is more accessible froin the outside than from within the calixarene cavity.