Alleno-Acetylenic Cage (AAC) Receptors: Chiroptical Switching and Enantioselective Complexation of trans-1,2-Dimethylcyclohexane in a Diaxial Conformation
Alleno-Acetylenic Cage (AAC) Receptors: Chiroptical Switching and Enantioselective Complexation of trans-1,2-Dimethylcyclohexane in a Diaxial Conformation
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DOI：
10.1002/anie.201607681
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发表时间：
2016-11-07
影响因子：
16.6
通讯作者：
Diederich, Francois
中科院分区：
文献类型：
--
作者：
Gropp, Cornelius;Trapp, Nils;Diederich, Francois
在间苯二酚[4]芳烃空穴的边缘连接了四个羟基末端的对映体1，3-二乙炔基烯(DEAs)。该体系经历了笼形和开放式之间的构象转换，笼型由环状氢键阵列封闭，叔醇基团向外延伸。在非极性溶剂中以笼状构象为主，在小分子极性溶剂中以开式构象为主。这两种状态在溶液中和X射线共晶结构中都得到了确认。异丙基乙炔笼(AAC)的电子捕获谱(ECD)是高度构象敏感的，在304 nm处最长的Cotton效应是从开环(P)(4)-AAC乙腈的Delta epsilon=+191M(-1)cm(-1)到闭合的(P)(4)-AAC的Delta epsilon=-691M(-1)cm(-1)(Delta epsilon=882M(-1)cm(-1))。在X-射线结构中发现了(垂直于)-反式-1，2-二甲基环己烷的完全手性拆分，其中(P)(4)-AAc与(R，R)-和(M)(4)-AAc与(S，S)-客体完全结合。客体包裹体以较高的能量二轴构象出现。
Four enantiopure 1,3-diethynylallenes (DEAs) with OH termini were attached to the rim of a resorcin[4] arene cavitand. The system undergoes conformational switching between a cage form, closed by a circular H-bonding array, and an open form, with the tertiary alcohol groups reaching outwards. The cage form is predominant in apolar solvents, and the open conformation in small, polar solvents. Both states were confirmed in solution and in X-ray co-crystal structures. ECD spectra of the alleno-acetylenic cages (AACs) are highly conformation sensitive, the longest wavelength Cotton effect at 304 nm switches from Delta epsilon= +191M(-1) cm(-1) for open (P)(4)-AAC subset of acetonitrile to Delta epsilon= -691M(-1) cm(-1) (Delta Delta epsilon= 882M(-1) cm(-1)) for closed (P)(4)-AAC subset of cyclohexane. Complete chiral resolution of (perpendicular to)-trans-1,2-dimethylcyclohexane was found in the X-ray structures, with (P)(4)-AAC exclusively bound to the (R, R)-and (M)(4)-AAC to the (S, S)-guest. Guest inclusion occurs in a higher energy diaxial conformation.