An Ultimate Stereocontrol in Supramolecular Photochirogenesis: Photocyclodimerization of 2-Anthracenecarboxylate Mediated by Sulfur-Linked β-Cyclodextrin Dimers
An Ultimate Stereocontrol in Supramolecular Photochirogenesis: Photocyclodimerization of 2-Anthracenecarboxylate Mediated by Sulfur-Linked β-Cyclodextrin Dimers
复制标题
超分子光手性发生的终极立体控制：硫连接的β-环糊精二聚体介导的2-蒽甲酸酯的光环二聚化
DOI：
10.1021/jacs.9b01993
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发表时间：
2019-06-12
影响因子：
15
通讯作者：
Yang, Cheng
中科院分区：
文献类型：
--
作者：
Ji, Jiecheng;Wu, Wanhua;Yang, Cheng
设计了一种以硫原子或芳烃为间隔基的β-环糊精（CD）二聚体的立体异构体，构建了一种栓系双CD胶囊，用于精确控制2-蒽甲酸酯（AC）光环化二聚为4种经典的9，10：9 '，10'-环二聚体和2种非经典的5，8：9 '，10'-环二聚体的区域选择性和对映选择性.在所制备的二聚体CD主体中，exo-3-thia-beta-CD二聚体与AC在水溶液中形成1：1和1：2的主客体络合物，前者阻碍AC光环化二聚，而后者促进AC光环化二聚，其区域选择性和对映体选择性远高于用天然beta-CD或其余beta-CD二聚体获得的那些。立体化学结果被证明是高度敏感的，因此可通过连接的糖单元的连接位置和构型以及连接体长度以及外部变量（如温度、pH和添加的盐）进行严格操纵。最终，由二聚体β-CD主体介导的AC的光环化二聚化在0.5 ℃的pH 5.1缓冲溶液中以及在-20 ℃的CsCl水溶液中以97-98%的产率得到对映体纯的顺式-头对尾-9，10：9 '，10'-环二聚体。
Stereoisomeric beta-cyclodextrin (CD) dimers linked with a sulfur atom or an arene spacer were designed to create a tethered dual CD capsule for precisely manipulating the regio-and enantioselectivities of the photocyclodimerization of 2-anthracenecarboxylate (AC) to four stereoisomeric classical 9,10:9',10'-cyclodimers and two nonclassical 5,8:9',10'-cyclodimers. Among the dimeric CD hosts prepared, exo-3-thia-beta-CD dimer formed 1:1 and 1:2 host guest complexes with AC in aqueous solutions, the former of which hindered but the latter facilitated the AC photocyclodimerization with regio-and enantioselectivities much higher than those obtained with native beta-CD or the rest of the beta-CD dimers. The stereochemical outcomes turned out to be highly sensitive to and hence critically manipulable by the linking position and configuration of the connected saccharide units and the linker length, as well as the external variants, such as temperature, pH, and added salt. Eventually, the photocyclodimerization of AC mediated by the dimeric beta-CD host gave enantiopure syn-head-to-tail-9,10:9',10'-cyclodimer in 97-98% yield in a pH 5.1 buffer solution at 0.5 degrees C and also in an aqueous CsCl solution at -20 degrees C.